WorldWideScience

Sample records for partially molten magma

  1. Partially molten magma ocean model

    International Nuclear Information System (INIS)

    Shirley, D.N.

    1983-01-01

    The properties of the lunar crust and upper mantle can be explained if the outer 300-400 km of the moon was initially only partially molten rather than fully molten. The top of the partially molten region contained about 20% melt and decreased to 0% at 300-400 km depth. Nuclei of anorthositic crust formed over localized bodies of magma segregated from the partial melt, then grew peripherally until they coverd the moon. Throughout most of its growth period the anorthosite crust floated on a layer of magma a few km thick. The thickness of this layer is regulated by the opposing forces of loss of material by fractional crystallization and addition of magma from the partial melt below. Concentrations of Sr, Eu, and Sm in pristine ferroan anorthosites are found to be consistent with this model, as are trends for the ferroan anorthosites and Mg-rich suites on a diagram of An in plagioclase vs. mg in mafics. Clustering of Eu, Sr, and mg values found among pristine ferroan anorthosites are predicted by this model

  2. Partial structures in molten AgBr

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Hiroki [Department of Condensed Matter Chemistry and Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan)], E-mail: ueno@gemini.rc.kyushu-u.ac.jp; Tahara, Shuta [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Science, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Kawakita, Yukinobu [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan); Kohara, Shinji [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Takeda, Shin' ichi [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560 (Japan)

    2009-02-21

    The structure of molten AgBr has been studied by means of neutron and X-ray diffractions with the aid of structural modeling. It is confirmed that the Ag-Ag correlation has a small but well-defined first peak in the partial pair distribution function whose tail penetrates into the Ag-Br nearest neighbor distribution. This feature on the Ag-Ag correlation is intermediate between that of molten AgCl (non-superionic melt) and that of molten AgI (superionic melt). The analysis of Br-Ag-Br bond angle reveals that molten AgBr preserves a rocksalt type local ordering in the solid phase, suggesting that molten AgBr is clarified as non-superionic melt like molten AgCl.

  3. Constraints on the rheology of the partially molten mantle from numerical models of laboratory experiments

    Science.gov (United States)

    Rudge, J. F.; Alisic Jewell, L.; Rhebergen, S.; Katz, R. F.; Wells, G. N.

    2015-12-01

    One of the fundamental components in any dynamical model of melt transport is the rheology of partially molten rock. This rheology is poorly understood, and one way in which a better understanding can be obtained is by comparing the results of laboratory deformation experiments to numerical models. Here we present a comparison between numerical models and the laboratory setup of Qi et al. 2013 (EPSL), where a cylinder of partially molten rock containing rigid spherical inclusions was placed under torsion. We have replicated this setup in a finite element model which solves the partial differential equations describing the mechanical process of compaction. These computationally-demanding 3D simulations are only possible due to the recent development of a new preconditioning method for the equations of magma dynamics. The experiments show a distinct pattern of melt-rich and melt-depleted regions around the inclusions. In our numerical models, the pattern of melt varies with key rheological parameters, such as the ratio of bulk to shear viscosity, and the porosity- and strain-rate-dependence of the shear viscosity. These observed melt patterns therefore have the potential to constrain rheological properties. While there are many similarities between the experiments and the numerical models, there are also important differences, which highlight the need for better models of the physics of two-phase mantle/magma dynamics. In particular, the laboratory experiments display more pervasive melt-rich bands than is seen in our numerics.

  4. Melt migration modeling in partially molten upper mantle

    Science.gov (United States)

    Ghods, Abdolreza

    The objective of this thesis is to investigate the importance of melt migration in shaping major characteristics of geological features associated with the partial melting of the upper mantle, such as sea-floor spreading, continental flood basalts and rifting. The partial melting produces permeable partially molten rocks and a buoyant low viscosity melt. Melt migrates through the partially molten rocks, and transfers mass and heat. Due to its much faster velocity and appreciable buoyancy, melt migration has the potential to modify dynamics of the upwelling partially molten plumes. I develop a 2-D, two-phase flow model and apply it to investigate effects of melt migration on the dynamics and melt generation of upwelling mantle plumes and focusing of melt migration beneath mid-ocean ridges. Melt migration changes distribution of the melt-retention buoyancy force and therefore affects the dynamics of the upwelling plume. This is investigated by modeling a plume with a constant initial melt of 10% where no further melting is considered. Melt migration polarizes melt-retention buoyancy force into high and low melt fraction regions at the top and bottom portions of the plume and therefore results in formation of a more slender and faster upwelling plume. Allowing the plume to melt as it ascends through the upper mantle also produces a slender and faster plume. It is shown that melt produced by decompressional melting of the plume migrates to the upper horizons of the plume, increases the upwelling velocity and thus, the volume of melt generated by the plume. Melt migration produces a plume which lacks the mushroom shape observed for the plume models without melt migration. Melt migration forms a high melt fraction layer beneath the sloping base of the impermeable oceanic lithosphere. Using realistic conditions of melting, freezing and melt extraction, I examine whether the high melt fraction layer is able to focus melt from a wide partial melting zone to a narrow region

  5. An experimental study of pressure shadows in partially molten rocks

    Science.gov (United States)

    Qi, Chao; Zhao, Yong-Hong; Kohlstedt, David L.

    2013-11-01

    As a two-phase, solid-melt material flows around rigid particles, melt-depleted and melt-enriched regions (i.e., pressure shadows) develop due to the coupled fluxes of melt and solid driven by pressure gradients around the particles. To study this compaction-decompaction process, samples composed of fine-grained San Carlos olivine plus mid-ocean ridge basalt containing dispersed sub-millimeter-sized, single crystal beads of olivine were deformed in torsion at a temperature of 1473 K and a confining pressure of 300 MPa. Indicated by melt distribution maps obtained from reflected-light optical and backscattered electron microscopy, melt-enriched and melt-depleted regions around the beads became observable at a local shear strain of γ≈1 in samples with an initially homogeneously distributed melt fraction of ϕ≈0.05. The melt-enriched regions (ϕbarhigh≈0.06 to 0.10) and the melt-depleted regions (ϕbarlow≈0.02 to 0.04), extending as far as one radius of the bead, were symmetrically distributed around the bead. The flow field of the olivine matrix determined from crystallographic preferred orientations agrees with theoretical predictions based on two-phase flow analysis. These experiments are the first to produce pressure shadows in partially molten rocks. One implication of this study is that it will be possible to constrain the ratio of bulk to shear viscosity, which is inferred from the distribution of melt using a combination of experimental observations and numerical simulations.

  6. Numerical analysis of partially molten splat during thermal spray process using the finite element method

    Science.gov (United States)

    Zirari, M.; Abdellah El-Hadj, A.; Bacha, N.

    2010-03-01

    A finite element method is used to simulate the deposition of the thermal spray coating process. A set of governing equations is solving by a volume of fluid method. For the solidification phenomenon, we use the specific heat method (SHM). We begin by comparing the present model with experimental and numerical model available in the literature. In this study, completely molten or semi-molten aluminum particle impacts a H13 tool steel substrate is considered. Next we investigate the effect of inclination of impact of a partially molten particle on flat substrate. It was found that the melting state of the particle has great effects on the morphologies of the splat.

  7. The Meaning of "Magma"

    Science.gov (United States)

    Bartley, J. M.; Glazner, A. F.; Coleman, D. S.

    2016-12-01

    Magma is a fundamental constituent of the Earth, and its properties, origin, evolution, and significance bear on issues ranging from volcanic hazards to planetary evolution. Unfortunately, published usages indicate that the term "magma" means distinctly different things to different people and this can lead to miscommunication among Earth scientists and between scientists and the public. Erupting lava clearly is magma; the question is whether partially molten rock imaged at depth and too crystal-rich to flow should also be called magma. At crystal fractions > 50%, flow can only occur via crystal deformation and solution-reprecipitation. As the solid fraction increases to 90% or more, the material becomes a welded crystal framework with melt in dispersed pores and/or along grain boundaries. Seismic images commonly describe such volumes of a few % melt as magma, yet the rheological differences between melt-rich and melt-poor materials make it vital not to confuse a large rock volume that contains a small melt fraction with melt-rich material. To ensure this, we suggest that "magma" be reserved for melt-rich materials that undergo bulk fluid flow on timescales consonant with volcanic eruptions. Other terms should be used for more crystal-rich and largely immobile partially molten rock (e.g., "crystal mush," "rigid sponge"). The distinction is imprecise but useful. For the press, the public, and even earth scientists who do not study magmatic systems, "magma" conjures up flowing lava; reports of a large "magma" body that contains a few percent melt can engender the mistaken perception of a vast amount of eruptible magma. For researchers, physical processes like crystal settling are commonly invoked to account for features in plutonic rocks, but many such processes are only possible in melt-rich materials.

  8. Mobility of partially molten crust, heat and mass transfer, and the stabilization of continents

    Science.gov (United States)

    Teyssier, Christian; Whitney, Donna L.; Rey, Patrice F.

    2017-04-01

    The core of orogens typically consists of migmatite terrains and associated crustal-derived granite bodies (typically leucogranite) that represent former partially molten crust. Metamorphic investigations indicate that migmatites crystallize at low pressure (cordierite stability) but also contain inclusions of refractory material (mafic, aluminous) that preserve evidence of crystallization at high pressure (HP), including HP granulite and eclogite (1.0-1.5 GPa), and in some cases ultrahigh pressure (2.5-3.0 GPa) when the continental crust was subducted (i.e. Norwegian Caledonides). These observations indicate that the partially molten crust originates in the deep crust or at mantle depths, traverses the entire orogenic crust, and crystallizes at shallow depth, in some cases at the near-surface ( 2 km depth) based on low-T thermochronology. Metamorphic assemblages generally show that this nearly isothermal decompression is rapid based on disequilibrium textures (symplectites). Therefore, the mobility of partially molten crust results in one of the most significant heat and mass transfer mechanisms in orogens. Field relations also indicate that emplacement of partially molten crust is the youngest major event in orogeny, and tectonic activity essentially ceases after the partially molten crust is exhumed. This suggests that flow and emplacement of partially molten crust stabilize the orogenic crust and signal the end of orogeny. Numerical modeling (open source software Underworld; Moresi et al., 2007, PEPI 163) provides useful insight into the mechanisms of exhumation of partially molten crust. For example, extension of thickened crust with T-dependent viscosity shows that extension of the shallow crust initially drives the mobility of the lowest viscosity crust (T>700°C), which begins to flow in a channel toward the zone of extension. This convergent flow generates channel collision and the formation of a double-dome of foliation (two subdomes separated by a steep

  9. Pressures of Partial Crystallization of Magmas Along Transforms: Implications for Crustal Accretion

    Science.gov (United States)

    Scott, J. L.; Zerda, C.; Brown, D.; Ciaramitaro, S. C.; Barton, M.

    2016-12-01

    Plate spreading at mid-ocean ridges is responsible for the creation of most of the crust on earth. The ridge system is very complex and many questions remain unresolved. Among these is the nature of magma plumbing systems beneath transform faults. Pervious workers have suggested that increased conductive cooling along transforms promotes higher pressures of partial crystallization, and that this explains the higher partial pressures of crystallization inferred for magmas erupted along slow spreading ridges compared to magmas erupted along faster spreading ridges. To test this hypothesis, we undertook a detailed analysis of pressures of partial crystallization for magmas erupted at 3 transforms along the fast to intermediate spreading East Pacific Rise(Blanco, Clipperton, and Siqueiros) and 3 transforms along the slow spreading Mid Atlantic Ridge(Famous Transform B, Kane, and 15°20'N). Pressures of partial crystallization were calculated from the compositions of glasses (quenched liquids) lying along the P (and T) dependent olivine, plagioclase, and augite cotectic using the method described by Kelley and Barton (2008). Published analyses of mid-ocean ridge basalt glasses sampled from these transforms and surrounding ridge segments were used as input data. Samples with anomalous chemical compositions and samples that yielded pressures associated with unrealistically large uncertainties were filtered out of the database. The pressures of partial crystallization for the remaining 916 samples ranged from 0 to 520 MPa with the great majority ( 95%) of sample returning pressures of less than 300 MPa. Pressures of 300 MPa) are associated with a small number of samples from the Pacific segments. Except for the Blanco, pressures of partial crystallization do not increase as transforms are approached. These observations contrast with those of previous workers, who reported anomalously high pressures (up to 1000 MPa) for a large number of samples erupted near both Atlantic

  10. Uranium and thorium concentration process during partial fusion and crystallization of granitic magma

    International Nuclear Information System (INIS)

    Cuney, M.

    1982-01-01

    Two major processes, frequently difficult to distinguish, lead to uranium and thorium enrichment in igneous rocks and more particularly in granitoids; these are partial melting and fractional crystallization. Mont-Laurier uranothoriferous pegmatoids, Bancroft and Roessing deposits are examples of radioelement concentrations resulting mostly of low grade of melting on essentially metasedimentary formations deposited on a continental margin or intracratonic. Fractional crystallization follows generally partial melting even in migmatitic areas. Conditions prevailing during magma crystallization and in particular oxygen fugacity led either to the formation of uranium preconcentrations in granitoids, or to its partition in the fluid phase expelled from the magma. No important economic uranium deposit appears to be mostly related to fractional crystallization of large plutonic bodies

  11. Numerical solution of a non-linear conservation law applicable to the interior dynamics of partially molten planets

    Science.gov (United States)

    Bower, Dan J.; Sanan, Patrick; Wolf, Aaron S.

    2018-01-01

    The energy balance of a partially molten rocky planet can be expressed as a non-linear diffusion equation using mixing length theory to quantify heat transport by both convection and mixing of the melt and solid phases. Crucially, in this formulation the effective or eddy diffusivity depends on the entropy gradient, ∂S / ∂r , as well as entropy itself. First we present a simplified model with semi-analytical solutions that highlights the large dynamic range of ∂S / ∂r -around 12 orders of magnitude-for physically-relevant parameters. It also elucidates the thermal structure of a magma ocean during the earliest stage of crystal formation. This motivates the development of a simple yet stable numerical scheme able to capture the large dynamic range of ∂S / ∂r and hence provide a flexible and robust method for time-integrating the energy equation. Using insight gained from the simplified model, we consider a full model, which includes energy fluxes associated with convection, mixing, gravitational separation, and conduction that all depend on the thermophysical properties of the melt and solid phases. This model is discretised and evolved by applying the finite volume method (FVM), allowing for extended precision calculations and using ∂S / ∂r as the solution variable. The FVM is well-suited to this problem since it is naturally energy conserving, flexible, and intuitive to incorporate arbitrary non-linear fluxes that rely on lookup data. Special attention is given to the numerically challenging scenario in which crystals first form in the centre of a magma ocean. The computational framework we devise is immediately applicable to modelling high melt fraction phenomena in Earth and planetary science research. Furthermore, it provides a template for solving similar non-linear diffusion equations that arise in other science and engineering disciplines, particularly for non-linear functional forms of the diffusion coefficient.

  12. Experimental test of the viscous anisotropy hypothesis for partially molten rocks.

    Science.gov (United States)

    Qi, Chao; Kohlstedt, David L; Katz, Richard F; Takei, Yasuko

    2015-10-13

    Chemical differentiation of rocky planets occurs by melt segregation away from the region of melting. The mechanics of this process, however, are complex and incompletely understood. In partially molten rocks undergoing shear deformation, melt pockets between grains align coherently in the stress field; it has been hypothesized that this anisotropy in microstructure creates an anisotropy in the viscosity of the aggregate. With the inclusion of anisotropic viscosity, continuum, two-phase-flow models reproduce the emergence and angle of melt-enriched bands that form in laboratory experiments. In the same theoretical context, these models also predict sample-scale melt migration due to a gradient in shear stress. Under torsional deformation, melt is expected to segregate radially inward. Here we present torsional deformation experiments on partially molten rocks that test this prediction. Microstructural analyses of the distribution of melt and solid reveal a radial gradient in melt fraction, with more melt toward the center of the cylinder. The extent of this radial melt segregation grows with progressive strain, consistent with theory. The agreement between theoretical prediction and experimental observation provides a validation of this theory.

  13. A hybrid composite dike suite from the northern Arabian Nubian Shield, southwest Jordan: Implications for magma mixing and partial melting of granite by mafic magma

    Science.gov (United States)

    Jarrar, Ghaleb H.; Yaseen, Najel; Theye, Thomas

    2013-03-01

    The Arabian Nubian Shield is an exemplary juvenile continental crust of Neoproterozoic age (1000-542 Ma). The post-collisional rift-related stage (~ 610 to 542 Ma) of its formation is characterized among others by the intrusion of several generations of simple and composite dikes. This study documents a suite of hybrid composite dikes and a natural example of partial melting of granite by a mafic magma from the northernmost extremity of Arabian Nubian Shield in southwest Jordan. The petrogenesis of this suite is discussed on the basis of field, petrographic, geochemical, and Rb/Sr isotopic data. These dikes give spectacular examples of the interaction between basaltic magma and the granitic basement. This interaction ranges from brecciation, partial melting of the host alkali feldspar granite to complete assimilation of the granitic material. Field structures range from intrusive breccia (angular partially melted granitic fragments in a mafic groundmass) to the formation of hybrid composite dikes that are up to 14 m in thickness. The rims of these dikes are trachyandesite (latite) with alkali feldspar ovoids (up to 1 cm in diameter); while the central cores are trachydacite to dacite and again with alkali feldspar ovoids and xenoliths from the dike rims. The granitic xenoliths in the intrusive breccia have been subjected to at least 33% partial melting. A seven-point Rb/Sr isochron from one of these composite dikes yields an age of 561 ± 33 Ma and an initial 87Sr/86Sr ratio of 0.70326 ± 0.0003 (2σ) and MSWD of 0.62. Geochemical modeling using major, trace, rare earth elements and isotopes suggests the generation of the hybrid composite dike suite through the assimilation of 30% to 60% granitic crustal material by a basaltic magma, while the latter was undergoing fractional crystallization at different levels in the continental crust.

  14. Direct evidence for the origin of low-18O silicic magmas: Quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

    International Nuclear Information System (INIS)

    Bacon, C.R.; Adami, L.H.; Lanphere, M.A.

    1989-01-01

    Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower δ 18 O values (-3.4 to +4.9per mille) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0per mille). Oxygen isotope fractionation between phases in granitoids is consistent with equilibrium at T≥900deg C following subsolidus exchange with hydrothermal fluids of meteoric origin. Assimilation of ≅ 10-20% of material similar to these granitoids can account for the O and Sr isotopic compositions of lavas and juvenile pyroclasts derived from the climactic magma chamber, many of which have δ 18 O values ≅ 0.5per mille or more lower than comparable lavas of Mount Mazama. The O isotope data provide the only clear evidence for such assimilation because the mineralogy and chemical and radiogenic isotopic compositions of the granitoids (dominantly granodiorite) are similar to those of erupted juvenile magmas. The granitoid blocks from Crater Lake serve as direct evidence for the origin of 18 O depletion in large, shallow silicic magma bodies. (orig.)

  15. South-Tibetan partially molten batholiths: geophysical characterization and petrological assessment of their origin

    Science.gov (United States)

    Hetényi, G.; Pistone, M.; Nabelek, P. I.; Baumgartner, L. P.

    2017-12-01

    Zones of partial melt in the middle crust of Lhasa Block, Southern Tibet, have been geophysically observed as seismically reflective "bright spots" in the past 20 years. These batholiths bear important relevance for geodynamics as they serve as the principal observation at depth supporting channel-flow models in the Himalaya-Tibet orogen. Here we assess the spatial abundance of and partial melt volume fraction within these crustal batholiths, and establish lower and upper estimate bounds using a joint geophysical-petrological approach.Geophysical imaging constrains the abundance of partial melt zones to 5.6 km3 per surface-km2 on average (minimum: 3.1 km3/km2, maximum: 7.6 km3/km2 over the mapped area). Physical properties detected by field geophysics and interpreted by laboratory measurements constrain the amount of partial melt to be between 5 and 26 percent.We evaluate the compatibility of these estimates with petrological modeling based on geotherms, crustal bulk rock compositions and water contents consistent with the Lhasa Block. These simulations determine: (a) the physico-chemical conditions of melt generation at the base of the Tibetan crust and its transport and emplacement in the middle crust; (b) the melt percentage produced at the source, transported and emplaced to form the observed "bright spots". Two main mechanisms are considered: (1) melting induced by fluids produced during mineral dehydration reactions in the underthrusting Indian lower crust; (2) dehydration-melting reactions caused by heating within the Tibetan crust. We find that both mechanisms demonstrate first-order match in explaining the formation of the partially molten "bright spots". Thermal modelling shows that the Lhasa Block batholiths have only small amounts of melt and only for geologically short times (features of the geodynamic evolution. Their transience excludes both long-distance and long-lasting channel flow transport in Tibet.

  16. Reactive transport in a partially molten system with binary solid solution

    Science.gov (United States)

    Jordan, J.; Hesse, M. A.

    2017-12-01

    Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the

  17. Electrical conductivity of partially-molten olivine aggregate and melt interconnectivity in the oceanic upper mantle

    Science.gov (United States)

    Laumonier, Mickael; Frost, Dan; Farla, Robert; Katsura, Tomoo; Marquardt, Katharina

    2016-04-01

    A consistent explanation for mantle geophysical anomalies such as the Lithosphere-Astenosphere Boundary (LAB) relies on the existence of little amount of melt trapped in the solid peridotite. Mathematical models have been used to assess the melt fraction possibly lying at mantle depths, but they have not been experimentally checked at low melt fraction (Lanzarote, Canary Islands, Spain) containing various amount of basaltic (MORB-like composition) melt (0 to 100%) at upper mantle conditions. We used the MAVO 6-ram press (BGI) combined with a Solartron gain phase analyser to acquire the electrical resistance of the sample at pressure of 1.5 GPa and temperature up to 1400°C. The results show the increase of the electrical conductivity with the temperature following an Arrhenius law, and with the melt fraction, but the effect of pressure between 1.5 and 3.0 GPa was found negligible at a melt fraction of 0.5 vol.%. The conductivity of a partially molten aggregate fits the modified Archie's law from 0.5 to 100 vol.%. At melt fractions of 0.25, 0.15 and 0.0 vol.%, the EC value deviates from the trend previously defined, suggesting that the melt is no longer fully interconnected through the sample, also supported by chemical mapping. Our results extend the previous results obtained on mixed system between 1 and 10% of melt. Since the melt appears fully interconnected down to very low melt fraction (0.5 vol.%), we conclude that (i) only 0.5 to 1 vol.% of melt is enough to explain the LAB EC anomaly, lower than previously determined; and (ii) deformation is not mandatory to enhance electrical conductivity of melt-bearing mantle rocks.

  18. Hot corrosion behavior of plasma-sprayed partially stabilized zirconia coatings in a lithium molten salt

    International Nuclear Information System (INIS)

    Cho, Soo Haeng; Hong, Sun Seok; Kang, Dae Seong; Park, Byung Heong; Hur, Jin Mok; Lee, Han Soo

    2008-01-01

    The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, Yttria-Stabilized Zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at 675 .deg. C for 216 hours in the molten salt LiCl-Li 2 O under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of LiCl-Li 2 O molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts

  19. Comparative Magma Oceanography

    Science.gov (United States)

    Jones, J. H.

    1999-01-01

    and, perhaps, mostly molten. The Giant Impact hypothesis for the origin of the Moon offers a tremendous input of thermal energy and the same could be true for core formation. And current solar system models favor the formation of a limited number of large (about 1000 km) planetesimals that, upon accreting to Earth, would cause great heating, being lesser versions of the Giant Impact. Several lines of geochemical evidence do not favor this hot early Earth scenario. (i) Terrestrial man-tle xenoliths are sometimes nearly chondritic in their major element compositions, suggesting that these rocks have never been much molten. Large degrees of partial melting probably promote differentiation rather than homogenization. (ii) Unlike the case of Mars, the continental crust probably did not form as a highly fractionated residual liquid from a magma ocean (about 99% crystallization), but, rather, formed in multiple steps. [The simplest model for the formation of continental crust is complicated: (a) about 10% melting of a primitive mantle, making basalt; (b) hydrothermal alteration of that basalt, converting it to greenstone; and (c) 10% partial melting of that greenstone, producing tonalite.] This model is reinforced by the recent observation from old (about 4.1 b.y.) zircons that the early crust formed from an undepleted mantle having a chondritic Lu/Hf ratio. (iii) If the mantle were once differentiated by a magma ocean, the mantle xenolith suite requires that it subsequently be homogenized. The Os isotopic compositions of fertile spinel lherzolites place constraints on the timing of that homogenization. The Os isotopic composition of spinel lherzolites approaches that of chondrites and correlates with elements such as Lu and Al. As Lu and Al concentrations approach those of the primitive mantle, Os isotopic compositions approach chondritic. The Re and Os in these xenoliths were probably added as a late veneer. Thus, the mantle that received the late veneer must have been

  20. Detachment folding of partially molten crust in accretionary orogens: A new magma-enhanced vertical mass and heat transfer mechanism

    Czech Academy of Sciences Publication Activity Database

    Lehmann, J.; Schulmann, K.; Lexa, O.; Závada, Prokop; Štípská, P.; Hasalová, Pavlína; Belyanin, G.; Corsini, M.

    2017-01-01

    Roč. 9, č. 6 (2017), s. 889-909 ISSN 1941-8264 Institutional support: RVO:67985530 Keywords : continental crust * shear-zone * gneiss domes Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.662, year: 2016

  1. Evidence for a magma reservoir beneath the Taipei metropolis of Taiwan from both S-wave shadows and P-wave delays.

    Science.gov (United States)

    Lin, Cheng-Horng

    2016-12-23

    There are more than 7 million people living near the Tatun volcano group in northern Taiwan. For the safety of the Taipei metropolis, in particular, it has been debated for decades whether or not these volcanoes are active. Here I show evidence of a deep magma reservoir beneath the Taipei metropolis from both S-wave shadows and P-wave delays. The reservoir is probably composed of either a thin magma layer overlay or many molten sills within thick partially molten rocks. Assuming that 40% of the reservoir is partially molten, its total volume could be approximately 350 km 3 . The exact location and geometry of the magma reservoir will be obtained after dense seismic arrays are deployed in 2017-2020.

  2. Mantle ingredients for making the fingerprint of Etna alkaline magmas: implications for shallow partial melting within the complex geodynamic framework of Eastern Sicily

    Science.gov (United States)

    Viccaro, Marco; Zuccarello, Francesco

    2017-09-01

    Mantle ingredients responsible for the signature of Etnean Na- and K-alkaline magmas and their relationships with short-term geochemical changes of the erupted volcanic rocks have been constrained through a partial melting model that considers major, trace elements and water contents in the produced liquids. Characteristics of the Etnean source for alkaline magmas have been supposed similar to those of the mantle accessible at a regional scale, namely below the Hyblean Plateau. The assumption that the Etnean mantle resembles the one beneath the Hyblean Plateau is justified by the large geochemical affinities of the Etnean hawaiites/K-trachybasalts and the Hyblean hawaiites/alkali basalts for what concerns both trace elements and isotope systematics. We have modeled partial melting of a composite source constituted by two rock types, inferred by lithological and geochemical features of the Hyblean xenoliths: 1) a spinel lherzolite bearing metasomatic, hydrous phases and 2) a garnet pyroxenite in form of veins intruded into the spinel lherzolite. The partial melting modeling has been applied to each rock type and the resulting primary liquids have been then mixed in various proportions. These compositions have been compared with some Etnean alkaline magmas of the post ∼60 ka activity, which were firstly re-equilibrated to mantle conditions through mass balance calculations. Our results put into evidence that concentrations of major and trace elements along with the water obtained from the modeling are remarkably comparable with those of Etnean melts re-equilibrated at primary conditions. Different proportions of the spinel lherzolite with variable modal contents of metasomatic phases and of the garnet pyroxenite can therefore account for the signature of a large spectrum of Etnean alkaline magmas and for their geochemical variability through time, emphasizing the crucial role played by compositional small-scale heterogeneity of the source. These heterogeneities are

  3. Effects of varying oxygen partial pressure on molten silicon-ceramic substrate interactions

    Science.gov (United States)

    Ownby, D. P.; Barsoum, M. W.

    1980-01-01

    The silicon sessile drop contact angle was measured on hot pressed silicon nitride, silicon nitride coated on hot pressed silicon nitride, silicon carbon coated on graphite, and on Sialon to determine the degree to which silicon wets these substances. The post-sessile drop experiment samples were sectioned and photomicrographs were taken of the silicon-substrate interface to observe the degree of surface dissolution and degradation. Of these materials, silicon did not form a true sessile drop on the SiC on graphite due to infiltration of the silicon through the SiC coating, nor on the Sialon due to the formation of a more-or-less rigid coating on the liquid silicon. The most wetting was obtained on the coated Si3N4 with a value of 42 deg. The oxygen concentrations in a silicon ribbon furnace and in a sessile drop furnace were measured using the protable thoria-yttria solid solution electrolyte oxygen sensor. Oxygen partial pressures of 10 to the minus 7 power atm and 10 to the minus 8 power atm were obtained at the two facilities. These measurements are believed to represent nonequilibrium conditions.

  4. Thermodynamic analysis of ANS binding to partially unfolded α-lactalbumin: correlation of endothermic to exothermic changeover with formation of authentic molten globules.

    Science.gov (United States)

    Kim, Ki Hyung; Yun, Soi; Mok, K H; Lee, E K

    2016-09-01

    A fluorescent reporter, 8-anilino-1-naphthalene sulfonic acid (ANS), can serve as a reference molecule for conformational transition of a protein because its aromatic carbons have strong affinity with hydrophobic cores of partially unfolded molten globules. Using a typical calcium-binding protein, bovine α-lactalbumin (BLA), as a model protein, we compared the ANS binding thermodynamics to the decalcified (10 mM EDTA treated) apo-BLA at two representative temperatures: 20 and 40 °C. This is because the authentic molten globule is known to form more heavily at an elevated temperature such as 40 °C. Isothermal titration calorimetry experiments revealed that the BLA-ANS interactions at both temperatures were entropy-driven, and the dissociation constants were similar on the order of 10(-4)  M, but there was a dramatic changeover in the binding thermodynamics from endothermic at 20 °C to exothermic at 40 °C. We believe that the higher subpopulation of authentic molten globules at 40 °C than 20 °C would be responsible for the results, which also indicate that weak binding is sufficient to alter the ANS binding mechanisms. We expect that the thermodynamic properties obtained from this study would serve as a useful reference for investigating the binding of other hydrophobic ligands such as oleic acid to apo-BLA, because oleic acid is known to have tumor-selective cytotoxicity when complexed with partially unfolded α-lactalbumin. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Superheat in magma oceans

    Science.gov (United States)

    Jakes, Petr

    1992-01-01

    The existence of 'totally molten' planets implies the existence of a superheat (excess of heat) in the magma reservoirs since the heat buffer (i.e., presence of crystals having high latent heat of fusion) does not exist in a large, completely molten reservoir. Any addition of impacting material results in increase of the temperature of the melt and under favorable circumstances heat is stored. The behavior of superheat melts is little understood; therefore, we experimentally examined properties and behavior of excess heat melts at atmospheric pressures and inert gas atmosphere. Highly siliceous melts (70 percent SiO2) were chosen for the experiments because of the possibility of quenching such melts into glasses, the slow rate of reaction in highly siliceous composition, and the fact that such melts are present in terrestrial impact craters and impact-generated glasses. Results from the investigation are presented.

  6. Evolution and dynamics of Earth from a molten initial stage

    Science.gov (United States)

    Louro Lourenço, D. J.; Tackley, P.

    2016-12-01

    It is now well established that most of the terrestrial planets underwent a magma ocean stage during their accretion. On Earth, it is probable that at the end of accretion, giant impacts like the hypothesised Moon-forming impact, together with other sources of heat, melted a substantial part of the mantle. The thermal and chemical evolution of the resulting magma ocean most certainly had dramatic consequences on the history of the planet. Considerable research has been done on magma oceans using simple 1-D models (e.g.: Abe, PEPI 1997; Solomatov, Treat. Geophys. 2007; Elkins-Tanton EPSL 2008). However, some aspects of the dynamics may not be adequately addressed in 1-D and require the use of 2-D or 3-D models. Moreover, new developments in mineral physics that indicate that melt can be denser than solid at high pressures (e.g.: de Koker et al., EPSL 2013) can have very important impacts on the classical views of the solidification of magma oceans (Labrosse et al., Nature 2007; Labrosse et al., The Early Earth 2015). The goal of our study is to understand and characterize the influence of melting on the long-term thermo-chemical evolution of rocky planet interiors, starting from an initial molten state (magma ocean). Our approach is to model viscous creep of the solid mantle, while parameterizing processes that involve melt as previously done in 1-D models, including melt-solid separation at all melt fractions, the use of an effective diffusivity to parameterize turbulent mixing, coupling to a parameterized core heat balance and a radiative surface boundary condition. These enhancements have been made to the numerical code StagYY (Tackley, PEPI 2008). We present results for the evolution of an Earth-like planet from a molten initial state to present day, while testing the effect of uncertainties in parameters such as melt-solid density differences, surface heat loss and efficiency of turbulent mixing. Our results show rapid cooling and crystallization until the

  7. Depths of Magma Chambers in the Icelandic Crust

    Science.gov (United States)

    Kelley, D. F.; Kapostasy, D. D.; Barton, M.

    2004-05-01

    There is considerable interest in the structure and thermal state of the crust in Iceland, which lies across the Mid Atlantic Ridge. However, interpretations of seismic and gravity data yield conflicting views of the nature of the lower crust. Some interpretations prefer a model in which the lower crust (15-25 km) is relatively cool and solid, whereas other interpretations, based largely on gravity data, prefer a model in which the lower crust is relatively warm and possibly partially molten. Knowledge of the depth of magma chambers is critical to constrain the geothermal gradient in Icelandic crust and to resolve discrepancies in interpretation of geophysical data. Analyses of aphyric lavas and of glasses in Icelandic lavas erupted from 11 volcanic centers have been compiled. The compositions are picritic and basaltic with SiO2 - 47 to 50 wt%, MgO - 6 to 15wt%, FeO - 8 to 14wt%, to, Na2O - 1.3 to 3.3 wt%, and K2O - 0.03-46 wt%. The pressures of equilibration of these liquids with ol, high-Ca pyx and plag were estimated qualitatively from projections into the pseudoternary system Ol-Di-Silica using methods described by Walker and coworkers and Grove and coworkers. The results (ca. 0.5 GPa) indicate crystallization in magma chambers located at about 16 km depth. Equilibration pressures were also calculated using the method described by Yang and coworkers and by a modified version of this method. Calculated pressures (0.45±0.15 GPa) indicate magma chambers located at 15±4 km depth. Equilibration pressures for Rekjanes Ridge glasses determined using the same techniques are 0.2±0.1 GPa, corresponding to depths of 7.6±3 km. The results indicate the presence of magma chambers in the deep Icelandic crust and that the latter is relatively warm. Shallower chambers (3-7 km) have been identified from seismic studies suggesting a complex magma plumbing system. The results also confirm that magma chambers beneath Iceland are located at greater depths than those beneath the

  8. Strain Distribution in a Partially Molten Crust: Insights from the AMS Study of Carlos Chagas Anatexite, ARAÇUAI Belt (se Brazil)

    Science.gov (United States)

    Cavalcante, G.; Silva, M.; Vauchez, A. R.

    2012-12-01

    Anatectic domains, characterized by abundant migmatites, represent portions of the middle crust that have been partially molten. The Carlos Chagas anatexite is a unit that includes diatexites, metaxites and anatetic, peraluminous granites. It is localized in eastern domain of the Araçuaí Belt, which was formed during the amalgamation of West Gondwana by the collision of the Sao Francisco and Congo cratons. This orogenic segment underwent a synkinematic high temperature (>750oC)-low pressure (~ 6MPa) metamorphism that causes widespread partial melting of the middle crust. The Carlos Chagas unit is composed by quartz, feldspar, garnet, biotite, sillimanite, ilmenite, rutile and cordierite. U-Pb data indicates that its crystallization occurred c. a. 574 ~ 3 Ma. The main feature of this migmatite is the presence of a pervasive magmatic foliation, which is marked by the preferential alignment of biotite, alkali feldspars and plagioclase. At the grain scale, quartz displays evidence of interstitial crystallization and few solid-state deformation fabrics are observed. We used anisotropy of magnetic susceptibility (AMS) as a tool for recovering mineral fabric and thus the flow field of the Carlos Chagas anatexite. Magnetic properties of 153 samples were measured. They yield dominantly low values of the bulk magnetic susceptibility (km 0) being dominantly more frequent than prolates ones. These magnetics characteristics are consistent with biotite being the dominant carrier of the AMS. Magnetic foliations and lineations suggest two main structural patterns. The northern portion of the studied area shows shallowly plunging lineations (02° - 20°) to SE (140°-120°) or NW (340°-300°), while the foliation strikes NW-SE with shallow dips (03°-10°). Local subvertical foliation dips (70°) are due to NE-SW trending transcurrent shear zones. The southern region shows complex magnetic fabric patterns. Magnetic lineation plunges range from 05° to 58°, in varied directions

  9. Late Neoproterozoic to Carboniferous genesis of A-type magmas in Avalonia of northern Nova Scotia: repeated partial melting of anhydrous lower crust in contrasting tectonic environments

    Science.gov (United States)

    Murphy, J. Brendan; Shellnutt, J. Gregory; Collins, William J.

    2018-03-01

    Avalonian rocks in northern mainland Nova Scotia are characterized by voluminous 640-600 Ma calc-alkalic to tholeiitic mafic to felsic magmas produced in a volcanic arc. However, after the cessation of arc activity, repeated episodes of felsic magmatism between ca. 580 Ma and 350 Ma are dominated by A-type geochemical characteristics. Sm-Nd isotopic data, combined with zircon saturation temperature estimates, indicate that these magmas were formed by high temperature (800-1050 °C) melting of the same anhydrous crustal source. Regional tectonic considerations indicate that A-type felsic magmatism was produced (1) at 580 Ma in a San Andreas-type strike slip setting, (2) at 495 Ma as Avalonia rifted off Gondwana, (3) at 465 and 455 in an ensialic island arc environment and (4) at 360-350 Ma during post-collisional, intra-continental strike-slip activity as Avalonia was translated dextrally along the Laurentian margin. These results attest to the importance of crustal source, rather than tectonic setting, in the generation of these A-type magmas and are an example of how additional insights are provided by comparing the geochemical and isotopic characteristics of igneous suites of different ages within the same terrane. They also suggest that the shallow crustal rocks in northern mainland Nova Scotia were not significantly detached from their lower crustal source between ca. 620 Ma and 350 Ma, a time interval that includes the separation of Avalonia from Gondwana, its drift and accretion to Laurentia as well as post-accretionary strike-slip displacement.

  10. The topotactic transformation of Ti3SiC2 into a partially ordered cubic Ti(C0.67Si0.06) phase by the diffusion of Si into molten cryolite

    International Nuclear Information System (INIS)

    Barsoum, M.W.; El-Raghy, T.; Farber, L.; Amer, M.; Christini, R.; Adams

    1999-01-01

    Immersion of Ti 3 SiC 2 samples in molten cryolite at 960 C resulted in the preferential diffusion of Si atoms out of the basal planes to form a partially ordered, cubic phase with approximate chemistry Ti(C 0.67 , Si 0.06 ). The latter forms in domains, wherein the (111) planes are related by mirror planes; i.e., the loss of Si results in the de-twinning of the Ti 3 C 2 layers. Raman spectroscopy, X-ray diffraction, optical, scanning and transmission electron microscopy all indicate that the Si exists the structure topotactically, in such a way that the C atoms remain partially in their ordered position in the cubic phase

  11. Chemical consequences of compaction within the freezing front of a crystallizing magma ocean

    Science.gov (United States)

    Hier-Majumder, S.; Hirschmann, M. M.

    2013-12-01

    The thermal and compositional evolution of planetary magma oceans have profound influences on the early development and differentiation of terrestrial planets. During crystallization, rejection of elements incompatible in precipitating solids leads to petrologic and geochemical planetary differentiation, including potentially development of a compositionally stratified early mantle and evolution of thick overlying atmospheres. In cases of extremely efficient segregation of melt and crystals, solidified early mantles can be nearly devoid of key incompatible species including heat-producing (U, Th, K) and volatile (H,C,N,& noble gas) elements. A key structural component of a crystallizing magma ocean is the partially molten freezing front. The dynamics of this region influences the distribution of incompatible elements between the earliest mantle and the initial surficial reservoirs. It also can be the locus of heating owing to the dissipation of large amounts of tidal energy potentially available from the early Moon. The dynamics are influenced by the solidification rate, which is coupled to the liberation of volatiles owing to the modulating greenhouse effects in the overlying thick atmosphere. Compaction and melt retention in the freezing front of a magma ocean has received little previous attention. While the front advances during the course of crystallization, coupled conservation of mass, momentum, and energy within the front controls distribution and retention of melt within this layer. Due to compaction within this layer, melt distribution is far from uniform, and the fraction of melt trapped within this front depends on the rate of freezing of the magma ocean. During phases of rapid freezing, high amount of trapped melt within the freezing front retains a larger quantity of dissolved volatiles and the reverse is true during slow periods of crystallization. Similar effects are known from inferred trapped liquid fractions in layered mafic intrusions. Here we

  12. Early evolution and dynamics of Earth from a molten initial stage

    Science.gov (United States)

    Louro Lourenço, Diogo; Tackley, Paul J.

    2016-04-01

    It is now well established that most of the terrestrial planets underwent a magma ocean stage during their accretion. On Earth, it is probable that at the end of accretion, giant impacts like the hypothesised Moon-forming impact, together with other sources of heat, melted a substantial part of the mantle. The thermal and chemical evolution of the resulting magma ocean most certainly had dramatic consequences on the history of the planet. Considerable research has been done on magma oceans using simple 1-D models (e.g.: Abe, PEPI 1997; Solomatov, Treat. Geophys. 2007; Elkins-Tanton EPSL 2008). However, some aspects of the dynamics may not be adequately addressed in 1-D and require the use of 2-D or 3-D models. Moreover, new developments in mineral physics that indicate that melt can be denser than solid at high pressures (e.g.: de Koker et al., EPSL 2013) can have very important impacts on the classical views of the solidification of magma oceans (Labrosse et al., Nature 2007). The goal of our study is to understand and characterize the influence of melting on the long-term thermo-chemical evolution of rocky planet interiors, starting from an initial molten state (magma ocean). Our approach is to model viscous creep of the solid mantle, while parameterizing processes that involve melt as previously done in 1-D models, including melt-solid separation at all melt fractions, the use of an effective diffusivity to parameterize turbulent mixing, coupling to a parameterized core heat balance and a radiative surface boundary condition. These enhancements have been made to the numerical code StagYY (Tackley, PEPI 2008). We present results for the evolution of an Earth-like planet from a molten initial state to present day, while testing the effect of uncertainties in parameters such as melt-solid density differences, surface heat loss and efficiency of turbulent mixing. Our results show rapid cooling and crystallization until the rheological transition then much slower

  13. Crystallization of Magma. CEGS Programs Publication Number 14.

    Science.gov (United States)

    Berry, R. W.

    Crystallization of Magma is one of a series of single-topic problem modules intended for use in undergraduate geology and earth science courses. Through problems and observations based on two sets of experiments, this module leads to an understanding of how an igneous rock can form from molten material. Environmental factors responsible for…

  14. El Hierro's floating stones as messengers of crust-magma interaction at depth

    Science.gov (United States)

    Burchardt, S.; Troll, V. R.; Schmeling, H.; Koyi, H.; Blythe, L. S.; Longpré, M. A.; Deegan, F. M.

    2012-04-01

    During the early stages of the submarine eruption that started on October 10 2011 south of El Hierro, Canary Islands, Spain, peculiar eruption products were found floating on the sea surface. These centimetre- to decimetre-sized "bombs" have been termed "restingolites" after the nearby village La Restinga and consist of a basaltic rind and a white to light grey core that resembles pumice in texture. According to Troll et al. (2011; see also Troll et al. EGU 2012 Abstracts), this material consists of a glassy matrix hosting extensive vesicle networks, which results in extremely low densities allowing these rocks to float on sea water. Mineralogical and geochemical analyses reveal that the "restingolites" originate from the sedimentary rocks (sand-, silt-, and mudstones) that form layer 1 of the oceanic crust beneath El Hierro. During the onset and early stages of the eruption, magma ponded at the base of this sedimentary sequence, breaking its way through the sedimentary rocks to the ocean floor. The textures of the "restingolites" reveal that crust-magma interaction during fragmentation and transport of the xenoliths involved rapid partial melting and volatile exsolution. Xenoliths strikingly similar to those from El Hierro are known from eruptions on other Canary Islands (e.g. La Palma, Gran Canaria, and Lanzarote). In fact, they resemble in texture xenoliths of various protoliths from volcanic areas worldwide (e.g. Krakatao, Indonesia, Cerro Quemado, Guatemala, Laacher See, Germany). This indicates that the process of partial melting and volatile exsolution, which the "restingolites" bear witness of, is probably occurring frequently during shallow crustal magma emplacement. Thermomechanical numerical models of the effect of the density decrease associated with the formation of vesicle networks in partially molten xenoliths show that xenoliths of crustal rocks initially sink in a magma chamber, but may start to float to the chamber roof once they start to heat up

  15. Geophysical Evidence for the Locations, Shapes and Sizes, and Internal Structures of Magma Chambers beneath Regions of Quaternary Volcanism

    Science.gov (United States)

    Iyer, H. M.

    1984-04-01

    This paper is a review of seismic, gravity, magnetic and electromagnetic techniques to detect and delineate magma chambers of a few cubic kilometres to several thousand cubic kilometres volume. A dramatic decrease in density and seismic velocity, and an increase in seismic attenuation and electrical conductivity occurs at the onset of partial melting in rocks. The geophysical techniques are based on detecting these differences in physical properties between solid and partially molten rock. Although seismic refraction techniques, with sophisticated instrumentation and analytical procedures, are routinely used for detailed studies of crustal structure in volcanic regions, their application for magma detection has been quite limited. In one study, in Yellowstone National Park, U.S.A., fan-shooting and time-term techniques have been used to detect an upper-crustal magma chamber. Attenuation and velocity changes in seismic waves from explosions and earthquakes diffracted around magma chambers are observed near some volcanoes in Kamchatka. Strong attenuation of shear waves from regional earthquakes, interpreted as a diffraction effect, has been used to model magma chambers in Alaska, Kamchatka, Iceland, and New Zealand. One of the most powerful techniques in modern seismology, the seismic reflection technique with vibrators, was used to confirm the existence of a strong reflector in the crust near Socorro, New Mexico, in the Rio Grande Rift. This reflector, discovered earlier from data from local earthquakes, is interpreted as a sill-like magma body. In the Kilauea volcano, Hawaii, mapping seismicity patterns in the upper crust has enabled the modelling of the complex magma conduits in the crust and upper mantle. On the other hand, in the Usu volcano, Japan, the magma conduits are delineated by zones of seismic quiescence. Three-dimensional modelling of laterally varying structures using teleseismic residuals is proving to be a very promising technique for detecting and

  16. Silicic magma generation at Askja volcano, Iceland

    Science.gov (United States)

    Sigmarsson, O.

    2009-04-01

    Rate of magma differentiation is an important parameter for hazard assessment at active volcanoes. However, estimates of these rates depend on proper understanding of the underlying magmatic processes and magma generation. Differences in isotope ratios of O, Th and B between silicic and in contemporaneous basaltic magmas have been used to emphasize their origin by partial melting of hydrothermally altered metabasaltic crust in the rift-zones favoured by a strong geothermal gradient. An alternative model for the origin of silicic magmas in the Iceland has been proposed based on U-series results. Young mantle-derived mafic protolith is thought to be metasomatized and partially melted to form the silicic end-member. However, this model underestimates the compositional variations of the hydrothermally-altered basaltic crust. New data on U-Th disequilibria and O-isotopes in basalts and dacites from Askja volcano reveal a strong correlation between (230Th/232Th) and delta 18O. The 1875 AD dacite has the lowest Th- and O isotope ratios (0.94 and -0.24 per mille, respectively) whereas tephra of evolved basaltic composition, erupted 2 months earlier, has significantly higher values (1.03 and 2.8 per mille, respectively). Highest values are observed in the most recent basalts (erupted in 1920 and 1961) inside the Askja caldera complex and out on the associated fissure swarm (Sveinagja basalt). This correlation also holds for older magma such as an early Holocene dacites, which eruption may have been provoked by rapid glacier thinning. Silicic magmas at Askja volcano thus bear geochemical signatures that are best explained by partial melting of extensively hydrothermally altered crust and that the silicic magma source has remained constant during the Holocene at least. Once these silicic magmas are formed they appear to erupt rapidly rather than mixing and mingling with the incoming basalt heat-source that explains lack of icelandites and the bi-modal volcanism at Askja

  17. Molten Globule-Like Partially Folded State of Bacillus licheniformis α-Amylase at Low pH Induced by 1,1,1,3,3,3-Hexafluoroisopropanol

    Directory of Open Access Journals (Sweden)

    Adyani Azizah Abd Halim

    2014-01-01

    Full Text Available Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP on acid-denatured Bacillus licheniformis α-amylase (BLA at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE222 nm up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0.

  18. Molten salt breeder reactor

    International Nuclear Information System (INIS)

    1977-01-01

    MSBR Study Group formed in October 1974 has studied molten salt breeder reactor and its various aspects. Usage of a molten salt fuel, extremely interesting as reactor chemistry, is a great feature to MSBR; there is no need for separate fuel making, reprocessing, waste storage facilities. The group studied the following, and these results are presented: molten salt technology, molten salt fuel chemistry and reprocessing, reactor characteristics, economy, reactor structural materials, etc. (Mori, K.)

  19. Molten-salt converter reactors

    International Nuclear Information System (INIS)

    Perry, A.M.

    1975-01-01

    Molten-salt reactors appear to have substantial promise as advanced converters. Conversion ratios of 0.85 to 0.9 should be attainable with favourable fuel cycle costs, with 235 U valued at $12/g. An increase in 235 U value by a factor of two or three ($10 to $30/lb. U 3 O 8 , $75/SWU) would be expected to increase the optimum conversion ratio, but this has not been analyzed in detail. The processing necessary to recover uranium from the fuel salt has been partially demonstrated in the MSRE. The equipment for doing this would be located at the reactor, and there would be no reliance on an established recycle industry. Processing costs are expected to be quite low, and fuel cycle optimization depends primarily on inventory and burnup or replacement costs for the fuel and for the carrier salt. Significant development problems remain to be resolved for molten-salt reactors, notably the control of tritium and the elimination of intergranular cracking of Hastelloy-N in contact with tellurium. However, these problems appear to be amenable to solution. It is appropriate to consider separating the development schedule for molten-salt reactors from that for the processing technology required for breeding. The Molten-Salt Converter Reactor should be a useful reactor in its own right and would be an advance towards the achievement of true breeding in thermal reactors. (author)

  20. Magma reservoir at Mt. Vesuvius: Deeper than 10 km

    International Nuclear Information System (INIS)

    Natale, M.; Luongo, G.; Nunziata, C.; Panza, G.F.

    2005-07-01

    One- and two-dimensional Vp models were obtained by TomoVes experiment, all characterized by low Vp in the uppermost 500 m and a sharp discontinuity at about 2-3 km beneath the volcano. Large amplitude late arrivals were identified as P- to S-phases converted at the top, between 8 and 10 km deep, of a low velocity layer with a dramatic drop of Vs, from approximately 3.6 km/s to less than 1.0 km/s. Here we synthesize the interpretation of Rayleigh wave dispersion measurements, made by several authors, to delineate the extent of such anomalous layer of hot, partially molten, crust material. Our non-linear inversion of broad-band dispersion measurements, gives a thickness not greater than 0.35 km, if we assume Vs equal to 1.0 km/s. The volume occupied by this very low velocity layer, sill shaped, is compatible with the size of Mt. Vesuvius cone, but it develops above a much larger hot mass which could be the parental source as the erupted products are only few percent of magma chamber. (author)

  1. Simulation, optimal control and parametric sensitivity analysis of a molten carbonate fuel cell using a partial differential algebraic dynamic equation system; Simulation, Optimale Steuerung und Sensitivitaetsanalyse einer Schmelzkarbonat-Brennstoffzelle mithilfe eines partiellen differential-algebraischen dynamischen Gleichungssystems

    Energy Technology Data Exchange (ETDEWEB)

    Sternberg, K

    2007-02-08

    Molten carbonate fuel cells (MCFCs) allow an efficient and environmentally friendly energy production by converting the chemical energy contained in the fuel gas in virtue of electro-chemical reactions. In order to predict the effect of the electro-chemical reactions and to control the dynamical behavior of the fuel cell a mathematical model has to be found. The molten carbonate fuel cell (MCFC) can indeed be described by a highly complex,large scale, semi-linear system of partial differential algebraic equations. This system includes a reaction-diffusion-equation of parabolic type, several reaction-transport-equations of hyperbolic type, several ordinary differential equations and finally a system of integro-differential algebraic equations which describes the nonlinear non-standard boundary conditions for the entire partial differential algebraic equation system (PDAE-system). The existence of an analytical or the computability of a numerical solution for this high-dimensional PDAE-system depends on the kind of the differential equations and their special characteristics. Apart from theoretical investigations, the real process has to be controlled, more precisely optimally controlled. Hence, on the basis of the PDAE-system an optimal control problem is set up, whose analytical and numerical solvability is closely linked to the solvability of the PDAE-system. Moreover the solution of that optimal control problem is made more difficult by inaccuracies in the underlying database, which does not supply sufficiently accurate values for the model parameters. Therefore the optimal control problem must also be investigated with respect to small disturbances of model parameters. The aim of this work is to analyze the relevant dynamic behavior of MCFCs and to develop concepts for their optimal process control. Therefore this work is concerned with the simulation, the optimal control and the sensitivity analysis of a mathematical model for MCDCs, which can be characterized

  2. Advancing dynamic and thermodynamic modelling of magma oceans

    Science.gov (United States)

    Bower, Dan; Wolf, Aaron; Sanan, Patrick; Tackley, Paul

    2017-04-01

    The techniques for modelling low melt-fraction dynamics in planetary interiors are well-established by supplementing the Stokes equations with Darcy's Law. But modelling high-melt fraction phenomena, relevant to the earliest phase of magma ocean cooling, necessitates parameterisations to capture the dynamics of turbulent flow that are otherwise unresolvable in numerical models. Furthermore, it requires knowledge about the material properties of both solid and melt mantle phases, the latter of which are poorly described by typical equations of state. To address these challenges, we present (1) a new interior evolution model that, in a single formulation, captures both solid and melt dynamics and hence charts the complete cooling trajectory of a planetary mantle, and (2) a physical and intuitive extension of a "Hard Sphere" liquid equation of state (EOS) to describe silicate melt properties for the pressure-temperature (P-T) range of Earth's mantle. Together, these two advancements provide a comprehensive and versatile modelling framework for probing the far-reaching consequences of magma ocean cooling and crystallisation for Earth and other rocky planets. The interior evolution model accounts for heat transfer by conduction, convection, latent heat, and gravitational separation. It uses the finite volume method to ensure energy conservation at each time-step and accesses advanced time integration algorithms by interfacing with PETSc. This ensures it accurately and efficiently computes the dynamics throughout the magma ocean, including within the ultra-thin thermal boundary layers (modelling capabilities. The thermodynamics of mantle melting are represented using a pseudo-one-component model, which retains the simplicity of a standard one-component model while introducing a finite temperature interval for melting (important for multi-component systems). Our new high P-T liquid EOS accurately captures the energetics and physical properties of the partially molten

  3. Molten salt electrorefining method

    International Nuclear Information System (INIS)

    Tanaka, Hiroshi; Nakamura, Hitoshi; Shoji, Yuichi; Matsumaru, Ken-ichi.

    1994-01-01

    A molten cadmium phase (lower side) and a molten salt phase (upper side) are filled in an electrolytic bath. A basket incorporating spent nuclear fuels is inserted/disposed in the molten cadmium phase. A rotatable solid cathode is inserted/disposed in the molten salt phase. The spent fuels, for example, natural uranium, incorporated in the basket is dissolved in the molten cadmium phase. In this case, the uranium concentration in the molten salt phase is determined as from 0.5 to 20wt%. Then, electrolysis is conducted while setting a stirring power for stirring at least the molten salt phase of from 2.5 x 10 2 to 1 x 10 4 based on a reynolds number. Crystalline nuclei of uranium are precipitated uniformly on the surface of the solid cathode, and they grow into fine dendrites. With such procedures, since short-circuit between the cathode precipitates and the molten cadmium phase (anode) is scarcely caused, to improve the recovering rate of uranium. (I.N.)

  4. Gases in molten salts

    CERN Document Server

    Tomkins, RPT

    1991-01-01

    This volume contains tabulated collections and critical evaluations of original data for the solubility of gases in molten salts, gathered from chemical literature through to the end of 1989. Within the volume, material is arranged according to the individual gas. The gases include hydrogen halides, inert gases, oxygen, nitrogen, hydrogen, carbon dioxide, water vapor and halogens. The molten salts consist of single salts, binary mixtures and multicomponent systems. Included also, is a special section on the solubility of gases in molten silicate systems, focussing on slags and fluxes.

  5. On the Role of Mantle Overturn during Magma Ocean Solidification

    Science.gov (United States)

    Boukaré, C. E.; Parmentier, E.; Parman, S. W.

    2017-12-01

    Solidification of potential global magma ocean(s) (MO) early in the history of terrestrial planets may play a key role in the evolution of planetary interiors by setting initial conditions for their long-term evolution. Constraining this initial structure of solid mantles is thus crucial but remains poorly understood. MO fractional crystallization has been proposed to generate gravitationally unstable Fe-Mg chemical stratification capable of driving solid-state mantle overturn. Fractional solidification and overturn hypothesis, while only an ideal limiting case, can explain important geochemical features of both the Moon and Mars. Current overturn models consider generally post-MO overturn where the cumulate pile remains immobile until the end of MO solidification. However, if the cumulate pile overturns during MO solidification, the general picture of early planet evolution might differ significantly from the static crystallization models. We show that the timing of mantle overturn can be characterized with a dimensionless number measuring the ratio of the MO solidification time and the purely compositional overturn timescale. Syn-solidification overturn occurs if this dimensionless parameter, Rc, exceeds a critical value. Rc is mostly affected by the competition between the MO solidification time and mantle viscosity. Overturn that occurs during solidification can result in smaller scales of mantle chemical heterogeneity that could persist for long times thus influencing the whole evolution of a planetary body. We will discuss the effects of compaction/percolation on mantle viscosity. If partially molten cumulate do not have time to compact during MO solidification, viscosity of cumulates would be significantly lower as the interstitcial melt fraction would be large. Both solid mantle remelting during syn-solidification overturn and porous convection of melt retained with the cumulates are expected to reduce the degree of fractional crystallization. Syn

  6. Metalcasting: Filtering Molten Metal

    International Nuclear Information System (INIS)

    Lauren Poole; Lee Recca

    1999-01-01

    A more efficient method has been created to filter cast molten metal for impurities. Read about the resulting energy and money savings that can accrue to many different industries from the use of this exciting new technology

  7. Mush Column Magma Chambers

    Science.gov (United States)

    Marsh, B. D.

    2002-12-01

    Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior

  8. Hydrogen isotopic fractionation during crystallization of the terrestrial magma ocean

    Science.gov (United States)

    Pahlevan, K.; Karato, S. I.

    2016-12-01

    Models of the Moon-forming giant impact extensively melt and partially vaporize the silicate Earth and deliver a substantial mass of metal to the Earth's core. The subsequent evolution of the terrestrial magma ocean and overlying vapor atmosphere over the ensuing 105-6 years has been largely constrained by theoretical models with remnant signatures from this epoch proving somewhat elusive. We have calculated equilibrium hydrogen isotopic fractionation between the magma ocean and overlying steam atmosphere to determine the extent to which H isotopes trace the evolution during this epoch. By analogy with the modern silicate Earth, the magma ocean-steam atmosphere system is often assumed to be chemically oxidized (log fO2 QFM) with the dominant atmospheric vapor species taken to be water vapor. However, the terrestrial magma ocean - having held metallic droplets in suspension - may also exhibit a much more reducing character (log fO2 IW) such that equilibration with the overlying atmosphere renders molecular hydrogen the dominant H-bearing vapor species. This variable - the redox state of the magma ocean - has not been explicitly included in prior models of the coupled evolution of the magma ocean-steam atmosphere system. We find that the redox state of the magma ocean influences not only the vapor speciation and liquid-vapor partitioning of hydrogen but also the equilibrium isotopic fractionation during the crystallization epoch. The liquid-vapor isotopic fractionation of H is substantial under reducing conditions and can generate measurable D/H signatures in the crystallization products but is largely muted in an oxidizing magma ocean and steam atmosphere. We couple equilibrium isotopic fractionation with magma ocean crystallization calculations to forward model the behavior of hydrogen isotopes during this epoch and find that the distribution of H isotopes in the silicate Earth immediately following crystallization represents an oxybarometer for the terrestrial

  9. Compositional variation through time and space in Quaternary magmas of the Chyulu Hills Volcanic Province, Kenya

    Science.gov (United States)

    Widom, E.; Kuentz, D. C.

    2017-12-01

    The Chyulu Hills Volcanic Province, located in southern Kenya >100 km east of the Kenya Rift Valley, has produced mafic, monogenetic eruptions throughout the Quaternary. The volcanic field is considered to be an off-rift manifestation of the East African Rift System, and is known for the significant compositional variability of its eruptive products, which range from nephelinites to basanites, alkali basalts, hawaiites, and orthopyroxene-normative subalkaline basalts [1]. Notably, erupted compositions vary systematically in time and space: Pleistocene volcanism, occurring in the northern Chyulu Hills, was characterized by highly silica-undersaturated magmas, whereas Holocene volcanism, restricted to the southern Chyulu Hills, is less silica-understaturated, consistent with a progressive decrease in depth and increase in degree of melting with time, from north to south [1]. Pronounced negative K anomalies, and enriched trace element and Sr-Nd-Pb isotope signatures have been attributed to a metasomatized, amphibole-bearing, sub-continental lithospheric mantle (SCLM) source [2]. Seismic evidence for a partially molten zone in the SCLM beneath this region [3] may be consistent with such an interpretation. We have analyzed Chyulu Hills samples for Os, Hf and high precision Pb isotopes to further evaluate the magma sources and petrogenetic processes leading to systematic compositional variation in time and space. Sr-Nd-Pb-Hf isotope systematics and strong negative correlations of 206Pb/204Pb and highly incompatible trace element ratios with SiO2 are consistent with the progression from a deeper, HIMU-type source to a shallower, EM-type source. Os isotope systematics, however, suggest a more complex relationship; although all samples are more radiogenic than primitive mantle, the least radiogenic values (similar to primitive OIB) are found in magmas with intermediate SiO2, and those with lower or higher SiO2 are more radiogenic. This may be explained by interaction

  10. The Surtsey Magma Series.

    Science.gov (United States)

    Schipper, C Ian; Jakobsson, Sveinn P; White, James D L; Michael Palin, J; Bush-Marcinowski, Tim

    2015-06-26

    The volcanic island of Surtsey (Vestmannaeyjar, Iceland) is the product of a 3.5-year-long eruption that began in November 1963. Observations of magma-water interaction during pyroclastic episodes made Surtsey the type example of shallow-to-emergent phreatomagmatic eruptions. Here, in part to mark the 50(th) anniversary of this canonical eruption, we present previously unpublished major-element whole-rock compositions, and new major and trace-element compositions of sideromelane glasses in tephra collected by observers and retrieved from the 1979 drill core. Compositions became progressively more primitive as the eruption progressed, with abrupt changes corresponding to shifts between the eruption's four edifices. Trace-element ratios indicate that the chemical variation is best explained by mixing of different proportions of depleted ridge-like basalt, with ponded, enriched alkalic basalt similar to that of Iceland's Eastern Volcanic Zone; however, the systematic offset of Surtsey compositions to lower Nb/Zr than other Vestmannaeyjar lavas indicates that these mixing end members are as-yet poorly contained by compositions in the literature. As the southwestern-most volcano in the Vestmannaeyjar, the geochemistry of the Surtsey Magma Series exemplifies processes occurring within ephemeral magma bodies on the extreme leading edge of a propagating off-axis rift in the vicinity of the Iceland plume.

  11. Lunar magma transport phenomena

    Science.gov (United States)

    Spera, Frank J.

    1992-01-01

    An outline of magma transport theory relevant to the evolution of a possible Lunar Magma Ocean and the origin and transport history of the later phase of mare basaltic volcanism is presented. A simple model is proposed to evaluate the extent of fractionation as magma traverses the cold lunar lithosphere. If Apollo green glasses are primitive and have not undergone significant fractionation en route to the surface, then mean ascent rates of 10 m/s and cracks of widths greater than 40 m are indicated. Lunar tephra and vesiculated basalts suggest that a volatile component plays a role in eruption dynamics. The predominant vapor species appear to be CO CO2, and COS. Near the lunar surface, the vapor fraction expands enormously and vapor internal energy is converted to mixture kinetic energy with the concomitant high-speed ejection of vapor and pyroclasts to form lunary fire fountain deposits such as the Apollo 17 orange and black glasses and Apollo 15 green glass.

  12. Magma ocean formation due to giant impacts

    Science.gov (United States)

    Tonks, W. B.; Melosh, H. J.

    1993-01-01

    The thermal effects of giant impacts are studied by estimating the melt volume generated by the initial shock wave and corresponding magma ocean depths. Additionally, the effects of the planet's initial temperature on the generated melt volume are examined. The shock pressure required to completely melt the material is determined using the Hugoniot curve plotted in pressure-entropy space. Once the melting pressure is known, an impact melting model is used to estimate the radial distance melting occurred from the impact site. The melt region's geometry then determines the associated melt volume. The model is also used to estimate the partial melt volume. Magma ocean depths resulting from both excavated and retained melt are calculated, and the melt fraction not excavated during the formation of the crater is estimated. The fraction of a planet melted by the initial shock wave is also estimated using the model.

  13. Eutectic propeties of primitive Earth's magma ocean

    Science.gov (United States)

    Lo Nigro, G.; Andrault, D.; Bolfan-Casanova, N.; Perillat, J.-P.

    2009-04-01

    It is widely accepted that the early Earth was partially molten (if not completely) due to the high energy dissipated by terrestrial accretion [1]. After core formation, subsequent cooling of the magma ocean has led to fractional crystallization of the primitive mantle. The residual liquid corresponds to what is now called the fertile mantle or pyrolite. Melting relations of silicates have been extensively investigated using the multi-anvil press, for pressures between 3 and 25 GPa [2,3]. Using the quench technique, it has been shown that the pressure affects significantly the solidus and liquidus curves, and most probably the composition of the eutectic liquid. At higher pressures, up to 65 GPa, melting studies were performed on pyrolite starting material using the laser-heated diamond anvil cell (LH-DAC) technique [4]. However, the quench technique is not ideal to define melting criteria, and furthermore these studies were limited in pressure range of investigation. Finally, the use of pyrolite may not be relevant to study the melting eutectic temperature. At the core-mantle boundary conditions, melting temperature is documented by a single data point on (Mg,Fe)2SiO4 olivine, provided by shock wave experiments at around 130-140 GPa [5]. These previous results present large uncertainties of ~1000 K. The aim of this study is to determine the eutectic melting temperature in the chemically simplified system composed of the two major lower mantle phases, the MgSiO3 perovskite and MgO periclase. We investigated melting in-situ using the laser-heated diamond anvil cell coupled with angle dispersive X-ray diffraction at the ID27 beamline of the ESRF [6]. Melting relations were investigated in an extended P-T range comparable to those found in the Earth's lower mantle, i.e. from 25 to 120 GPa and up to more than 5000 K. Melting was evidenced from (a) disappearance of one of the two phases in the diffraction pattern, (b) drastic changes of the diffraction image itself, and

  14. Drilling Magma for Science, Volcano Monitoring, and Energy

    Science.gov (United States)

    Eichelberger, J. C.; Lavallée, Y.; Blankenship, D.

    2017-12-01

    Magma chambers are central to understanding magma evolution, formation of continental crust, volcanism, and renewal of hydrothermal systems. Information from geology, petrology, laboratory experiments, and geophysical imagery has led to little consensus except a trend to see magma systems as being crystal-dominant (mush) rather than melt dominant. At high melt viscosities, crystal-liquid fractionation may be achieved by separation of melt from mush rather than crystals from liquid suspension. That the dominant volume has properties more akin to solid than liquid might explain the difficulty in detecting magma geophysically. Recently, geothermal drilling has intersected silicic magma at the following depths and SiO2 contents are: Puna, Hawaii, 2.5 km, 67 wt%; Menengai, Kenya 2.1 km, 67 wt%; Krafla, Iceland, 2.1 km, 75 wt%. Some similarities are: 1) Drillers encountered a "soft", sticky formation; 2) Cuttings or chips of clear quenched glass were recovered; 3) The source of the glass flowed up the well; 4) Transition from solid rock to recovering crystal-poor glass occurred in tens of meters, apparently without an intervening mush zone. Near-liquidus magma at the roof despite rapid heat loss there presents a paradox that may be explained by very recent intrusion of magma, rise of liquidus magma to the roof replacing partially crystallized magma, or extremely skewed representation of melt over mush in cuttings (Carrigan et al, this session). The latter is known to occur by filter pressing of ooze into lava lake coreholes (Helz, this session), but cannot be verified in actual magma without coring. Coring to reveal gradients in phase composition and proportions is required for testing any magma chamber model. Success in drilling into and controlling magma at all three locations, in coring lava lakes to over 1100 C, and in numerical modeling of coring at Krafla conditions (Su, this session) show this to be feasible. Other unprecedented experiments are using the known

  15. Why Is There an Abrupt Transition from Solid Rock to Low Crystallinity Magma in Drilled Magma Bodies?

    Science.gov (United States)

    Eichelberger, J. C.; Carrigan, C. R.; Sun, Y.; Lavallée, Y.

    2017-12-01

    We report on a preliminary evaluation, from basic principles of heat and mass transfer, on the unexpectedly abrupt transition from cuttings of solid rock to fragments of crystal poor glass during drilling into magma bodies. Our analysis is based on conditions determined and inferred for the 2009 IDDP-1 well in Krafla Caldera, which entered apparently liquidus rhyolite magma at about 900oC at a depth of 2104 m. Simple conduction would predict some 30 m of crystallization and partial crystallization since the latest time the magma could have been intruded, approximately 30 years prior to discovery by drilling. Option 1: The expected crystallization of magma has occurred but interstitial melt remains. The pressure difference between lithostatic load of about 50 MPa on the mush and 20 MPa hydrostatic pressure in the well causes pore melt to flow from the permeable mush into the borehole, where it becomes the source of the quenched melt chips. To be viable, this mechanism must work over the time frame of a day. Option 2: The expected crystallization is occurring, but high Rayleigh number thermal convection in the magma chamber continuously displaces crystallizing roof magma by liquidus magma from the interior of the body. To be viable, this mechanism must result in overturning magma in the chamber on a time scale that is much shorter than that of crystallization. Option 3: Flow-induced crystal migration away from zones of high shear created during drilling into magma may preferentially produce low-crystal-content melt at the boundary of the borehole, which is then sampled.

  16. Molten salt reactors

    International Nuclear Information System (INIS)

    Bouchter, J.C.; Dufour, P.; Guidez, J.; Simon, N.; Renault, C.

    2014-01-01

    Molten salt reactors are one of the 6 concepts retained for the 4. generation of nuclear reactors. The principle of this reactor is very innovative: the nuclear fuel is dissolved in the coolant which allows the online reprocessing of the fuel and the online recovery of the fission products. A small prototype: the Molten Salt Reactor Experiment (MSRE - 8 MWt) was operating a few years in the sixties in the USA. The passage towards a fast reactor by the suppression of the graphite moderator leads to the concept of Molten Salt Fast Reactor (MSFR) which is presently studied through different European projects such as MOST, ALISIA and EVOL. Worldwide the main topics of research are: the adequate materials resisting to the high level of corrosiveness of the molten salts, fuel salt reprocessing, the 3-side coupling between neutron transport, thermohydraulics and thermo-chemistry, the management of the changing chemical composition of the salt, the enrichment of lithium with Li 7 in the case of the use of lithium fluoride salt and the use of MSFR using U 233 fuel (thorium cycle). The last part of the article presents a preliminary safety analysis of the MSFR. (A.C.)

  17. Molten salt reactors: chemistry

    International Nuclear Information System (INIS)

    1983-01-01

    This work is a critical analysis of the 1000 MW MSBR project. Behavior of rare gases in the primary coolant circuit, their extraction from helium. Coating of graphite by molybdenum, chemistry of protactinium and niobium produced in the molten salt, continuous reprocessing of the fuel salt and use of stainless steel instead of hastelloy are reviewed [fr

  18. Molten fluoride fuel salt chemistry

    International Nuclear Information System (INIS)

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed. copyright American Institute of Physics 1995

  19. A glassy lava flow from Toconce volcano and its relation with the Altiplano-Puna Magma Body in Central Andes

    Science.gov (United States)

    Godoy, B.; Rodriguez, I.; Aguilera, F.

    2012-12-01

    Toconce is a composite stratovolcano located at the San Pedro - Linzor volcanic chain (SPLVC). This volcanic chain distributes within the Altiplano-Puna region (Central Andes) which is characterized by extensive rhyodacitic-to-rhyolitic ignimbritic fields, and voluminous domes of dacitic-to-rhyolitic composition (de Silva, 1989). The felsic melts that gave origin to ignimbrites and domes at this area were generated by mixing of mantle-derived magmas and anatectic melts assimilated during their ascent through the thick crust. Thus, partially molten layers exist in the upper crust below the APVC (de Silva et al., 2006). Evidence of large volumes of such melts has been also proposed by geophysical methods (i.e. the Altiplano-Puna Magma Body; Chmielowsky et al., 1999) In this work, petrography and whole rock, mineralogical and melt inclusions geochemistry of a glassy lava flow of Toconce volcano are presented. Petrographically, this lava flow shows a porphyric texture, with euhdral to subhedral plagioclase, ortho- and clino-pyroxene phenocrysts immersed in a glassy groundmass. Geochemically, the lava flow has 64.7% wt. SiO2. The glassy groundmass (~70% wt. SiO2) is more felsic than all the lavas in the volcanic chain (47-68% wt., Godoy et al., 2011). Analyzed orthopyroxene-hosted melt inclusions show an even higher SiO2 content (72-75% wt.), and a decreasing on Al2O3, Na2O, and CaO content with differentiation. Crystallization pressures of this lava flow, obtained using Putirka's two-pyroxene and clinopyroxene-liquid models (Putirka, 2008), range between 6 and 9 kbar. According to crystallization pressures, and major element composition, a felsic source located at shallow crustal pressures - where plagioclase is a stable mineralogical phase - originated the inclusions. This could be related to the presence of the Altiplano-Puna Magma Body (APMB) located below SPLVC. On the other hand, glassy groundmass, and disequilibrium textures in minerals of this lava flow could

  20. Molten salt reactors. The AMSTER concept

    International Nuclear Information System (INIS)

    Vergnes, J.; Garzenne, C.; Lecarpentier, D.; Mouney, H.

    2001-01-01

    This article presents the concept of actinide molten salt transmuter (AMSTER). This reactor is graphite-moderated and is dedicated to the burning of actinides. The main difference with a molten salt reactor is that its liquid fuel undergoes an on-line partial reprocessing in which fission products are extracted and heavy nuclei are reintroduced into the fuel. In order to maintain the reactivity regular injections of 235 U-salt are made. In classical reactors, fuel burn-up is limited by the swelling of the cladding and the radiation fuel pellets resistance, in AMSTER there is no limitation to the irradiation time of the fuel, so all the actinides can be burnt or transmuted. (A.C.)

  1. Molten salt breeder reactor

    International Nuclear Information System (INIS)

    Furukawa, Kazuo; Tsukada, Kineo; Nakahara, Yasuaki; Oomichi, Toshihiko; Oono, Hideo.

    1982-01-01

    Purpose: To simplify the structure, as well as improve the technical reliability and safety by the elimination of a proton beam entering window. Constitution: The nuclear reactor container main body is made of Hastelloy N and provided at the inner surface with two layers of graphite shields except for openings. An aperture was formed in the upper surface of the container, through which protons accelerated by a linear accelerator are directly entered to the liquid surface of molten salts such as 7LiF-BeF 2 -ThF 4 , 7LiF-NaF-ThF 4 , 7LiF-Rb-UF 4 , NaF-KF-UF 4 and the like. The heated molten salts are introduced by way of a pipeway into a heat exchanger where the heat is transferred to coolant salts and electric generation is conducted by way of heated steams. (Furukawa, Y.)

  2. Molten core retention assembly

    International Nuclear Information System (INIS)

    Lampe, R.F.

    1976-01-01

    Molten fuel produced in a core overheating accident is caught by a molten core retention assembly consisting of a horizontal baffle plate having a plurality of openings therein, heat exchange tubes having flow holes near the top thereof mounted in the openings, and a cylindrical imperforate baffle attached to the plate and surrounding the tubes. The baffle assembly is supported from the core support plate of the reactor by a plurality of hanger rods which are welded to radial beams passing under the baffle plate and intermittently welded thereto. Preferably the upper end of the cylindrical baffle terminates in an outwardly facing lip to which are welded a plurality of bearings having slots therein adapted to accept the hanger rods

  3. Adakitic magmas: modern analogues of Archaean granitoids

    Science.gov (United States)

    Martin, Hervé

    1999-03-01

    Both geochemical and experimental petrological research indicate that Archaean continental crust was generated by partial melting of an Archaean tholeiite transformed into a garnet-bearing amphibolite or eclogite. The geodynamic context of tholeiite melting is the subject of controversy. It is assumed to be either (1) subduction (melting of a hot subducting slab), or (2) hot spot (melting of underplated basalts). These hypotheses are considered in the light of modern adakite genesis. Adakites are intermediate to felsic volcanic rocks, andesitic to rhyolitic in composition (basaltic members are lacking). They have trondhjemitic affinities (high-Na 2O contents and K 2O/Na 2O˜0.5) and their Mg no. (0.5), Ni (20-40 ppm) and Cr (30-50 ppm) contents are higher than in typical calc-alkaline magmas. Sr contents are high (>300 ppm, until 2000 ppm) and REE show strongly fractionated patterns with very low heavy REE (HREE) contents (Yb≤1.8 ppm, Y≤18 ppm). Consequently, high Sr/Y and La/Yb ratios are typical and discriminating features of adakitic magmas, indicative of melting of a mafic source where garnet and/or hornblende are residual phases. Adakitic magmas are only found in subduction zone environments, exclusively where the subduction and/or the subducted slab are young (subducted and where the adakitic character of the lavas correlates well with the young age of the subducting oceanic lithosphere. In typical subduction zones, the subducted lithosphere is older than 20 Ma, it is cool and the geothermal gradient along the Benioff plane is low such that the oceanic crust dehydrates before it reaches the solidus temperature of hydrated tholeiite. Consequently, the basaltic slab cannot melt. The released large ion lithophile element (LILE)-rich fluids rise up into the mantle wedge, inducing both its metasomatism and partial melting. Afterwards, the residue is made up of olivine+clinopyroxene+orthopyroxene, such that the partial melts are HREE-rich (low La/Yb and Sr

  4. Numerical modeling of magma-repository interactions

    NARCIS (Netherlands)

    Bokhove, Onno

    2001-01-01

    This report explains the numerical programs behind a comprehensive modeling effort of magma-repository interactions. Magma-repository interactions occur when a magma dike with high-volatile content magma ascends through surrounding rock and encounters a tunnel or drift filled with either a magmatic

  5. Thermohydraulic behaviour and heat transfer in the molten core

    International Nuclear Information System (INIS)

    Reineke, H.H.

    1977-01-01

    Increasing the application of nuclear reactors to produce electrical power extremely unprobable accidents should be investigated too. In the Federal Republic of Germany, a research program is performed for some years engaged in accidents at light water reactors in which the melting of the reactor core is presumed. A part of this program is to investigate the thermohydraulic and the heat transfer behavior in an accumulation of molten core material. The knowledge of these events is necessary to analyse the accident exactly. Further on the results of this work are of great importance to build a catcher for the molten core material. As a result of the decay heat the molten material is heated up and the density differences induce a free convection motion. In this work the thermohydraulic behavior and the distribution of the escaping heat fluxes for several accumulations of molten core material were determined. The numerical methods for solving the system of partial differential equation were used to develop computer codes, able to compute the average and local heat fluxes at the walls enclosing the molten core material and the inside increase of the temperature. The numerical computations were confirmed and verified by experimental investigations. In these investigations the molten core material was always assumed as a homogeneous fluid. In this case, the results could be reproduced by simple power laws

  6. Magma emplacement in 3D

    Science.gov (United States)

    Gorczyk, W.; Vogt, K.

    2017-12-01

    Magma intrusion is a major material transfer process in Earth's continental crust. Yet, the mechanical behavior of the intruding magma and its host are a matter of debate. In this study, we present a series of numerical thermo-mechanical experiments on mafic magma emplacement in 3D.In our model, we place the magmatic source region (40 km diameter) at the base of the mantle lithosphere and connect it to the crust by a 3 km wide channel, which may have evolved at early stages of magmatism during rapid ascent of hot magmatic fluids/melts. Our results demonstrate continental crustal response due to magma intrusion. We observe change in intrusion geometries between dikes, cone-sheets, sills, plutons, ponds, funnels, finger-shaped and stock-like intrusions as well as injection time. The rheology and temperature of the host-rock are the main controlling factors in the transition between these different modes of intrusion. Viscous deformation in the warm and deep crust favours host rock displacement and magma pools along the crust-mantle boundary forming deep-seated plutons or magma ponds in the lower to middle-crust. Brittle deformation in the cool and shallow crust induces cone-shaped fractures in the host rock and enables emplacement of finger- or stock-like intrusions at shallow or intermediate depth. A combination of viscous and brittle deformation forms funnel-shaped intrusions in the middle-crust. Low-density source magma results in T-shaped intrusions in cross-section with magma sheets at the surface.

  7. Detection and removal of molten salts from molten aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    K. Butcher; D. Smith; C. L. Lin; L. Aubrey

    1999-08-02

    Molten salts are one source of inclusions and defects in aluminum ingots and cast shapes. A selective adsorption media was used to remove these inclusions and a device for detection of molten salts was tested. This set of experiments is described and the results are presented and analyzed.

  8. Ion diffusion related to structure in molten salts

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1996-08-01

    A model first developed by Zwanzig to derive transport coefficients in cold dense fluids directly from the Green-Kubo time correlation formulae allows one to relate macroscopic diffusion coefficients to the local fluid structure. Applications to various ionic diffusion processes in molten salts are reviewed. Consequences of partial structural quenching are also discussed. (author). 28 refs, 3 tabs

  9. Structure and thermodynamic properties of molten rubidium chloride

    International Nuclear Information System (INIS)

    Ballone, P.; Pastore, G.; Tosi, M.P.; Trieste Univ.

    1984-02-01

    Self-consistent calculations of partial pair distribution functions and thermodynamic properties are presented for molten RbCl in a non-polarizable-ion model and compared with computer simulation data. The theory, which is quantitatively very successful, hinges on an empirical evaluation of bridge diagrams including both excluded-volume effects and long-range Coulomb effects. (author)

  10. Molten carbonate fuel cell

    Science.gov (United States)

    Kaun, T.D.; Smith, J.L.

    1986-07-08

    A molten electrolyte fuel cell is disclosed with an array of stacked cells and cell enclosures isolating each cell except for access to gas manifolds for the supply of fuel or oxidant gas or the removal of waste gas. The cell enclosures collectively provide an enclosure for the array and effectively avoid the problems of electrolyte migration and the previous need for compression of stack components. The fuel cell further includes an inner housing about and in cooperation with the array enclosure to provide a manifold system with isolated chambers for the supply and removal of gases. An external insulated housing about the inner housing provides thermal isolation to the cell components.

  11. Thermal conductivity of molten metals

    Energy Technology Data Exchange (ETDEWEB)

    Peralta-Martinez, Maria Vita

    2000-02-01

    A new instrument for the measurement of the thermal conductivity of molten metals has been designed, built and commissioned. The apparatus is based on the transient hot-wire technique and it is intended for operation over a wide range of temperatures, from ambient up to 1200 K, with an accuracy approaching 2%. In its present form the instrument operates up to 750 K. The construction of the apparatus involved four different stages, first, the design and construction of the sensor and second, the construction of an electronic system for the measurement and storage of data. The third stage was the design and instrumentation of the high temperature furnace for the melting and temperature control of the sample, and finally, an algorithm was developed for the extraction of the thermal conductivity from the raw measurement data. The sensor consists of a cylindrical platinum-wire symmetrically sandwiched between two rectangular plane sheets of alumina. The rectangular sensor is immersed in the molten metal of interest and a voltage step is applied to the ends of the platinum wire to induce heat dissipation and a consequent temperature rise which, is in part, determined by the thermal conductivity of the molten metal. The process is described by a set of partial differential equations and appropriate boundary conditions rather than an approximate analytical solution. An electronic bridge configuration was designed and constructed to perform the measurement of the resistance change of the platinum wire in the time range 20 {mu}s to 1 s. The resistance change is converted to temperature change by a suitable calibration. From these temperature measurements as a function of time the thermal conductivity of the molten metals has been deduced using the Finite Element Method for the solution of the working equations. This work has achieved its objective of improving the accuracy of the measurement of the thermal conductivity of molten metals from {+-}20% to {+-}2%. Measurements

  12. The Magma Chamber Simulator: Modeling the Impact of Wall Rock Composition on Mafic Magmas during Assimilation-Fractional Crystallization

    Science.gov (United States)

    Creamer, J. B.; Spera, F. J.; Bohrson, W. A.; Ghiorso, M. S.

    2012-12-01

    C while in the second example features a WR beginning at 700oC due to prior regional heating from magmatic activity. In the first example, the Magma only experiences FC as it completely crystallizes before the WR is heated above the solidus. In the second example, identical beyond WR starting temperature, the Magma begins to receive anatectic melt from the granitic WR after ~10% of its original mass has crystallized. Once the Magma in the AFC example has reached an SiO2 content of 60 wt.%, the relative masses of 'initial Magma melt' : 'remaining melt in Magma' : 'cumulates' : 'cumulative anatectic melt added' is 1:1.4:0.1:0.5 as orthopyroxene follows olivine crystallization once assimilation begins. At the equivalent point of 60 wt.% SiO2 in the first FC-only case, these mass ratios sit at 1:0.35:0.65:0, as clinopyroxene and plagioclase follow olivine crystallization. In the second example with AFC, the assimilation dramatically modifies the chemical evolution of the magma as described above until a point where, in the WR, alkali feldspar has been exhausted by partial melting at the plag-kspar-qtz ternary minimum and the WR melt production rate slows for given heat input. Beyond these examples, the influence of WR composition on the chemical trends of an evolving set of mafic magmas undergoing AFC is portrayed.

  13. Molten fuel studies at Winfrith

    International Nuclear Information System (INIS)

    Edwards, A.J.; Knowles, J.B.; Tattersall, R.B.

    1988-01-01

    This report describes the experimental facilities available for molten fuel studies at Winfrith. These include a large facility capable of testing components at full LMFBR subassembly scale and also a high pressure facility for experiments at pressures up to 25 MPa, covering the whole range of temperatures and pressures of interest for the PWR. If the hypothetical accident conditions initiating the release of molten fuel do not produce an explosive transfer of thermal energy on contact of molten fuel with the reactor coolant, then an intermediate rate of heat transfer over several hundred milliseconds may occur. Theoretical work is described which is being carried out to predict the resulting pressurisation and the degree of mechanical loading on the reactor structure. Finally the current programme of molten fuel studies and recent progress are reviewed, and future plans, which are chiefly focussed on the study of thermal interactions between molten fuel and sodium coolant for the LMFBR are outlined. (author)

  14. Molten salt reactor concept

    International Nuclear Information System (INIS)

    Sood, D.D.

    1980-01-01

    Molten salt reactor is an advanced breeder concept which is suited for the utilization of thorium for nuclear power production. This reactor is based on the use of solutions of uranium or plutonium fluorides in LiF-BeF 2 -ThF 4 as fuel. Unlike the conventional reactors, no external coolant is used in the reactor core and the fuel salt itself is circulated through heat exchangers to transfer the fission produced heat to a secondary salt (NaF-NaBF 4 ) for steam generation. A part of the fuel stream is continuously processed to isolate 233 Pa, so that it can decay to fissile 233 U without getting converted to 234 Pa, and for the removal of neutron absorbing fission products. This on-line processing scheme makes this reactor concept to achieve a breeding ratio of 1.07 which is the highest for any thermal breeder reactor. Experimental studies at the Bhabha Atomic Research Centre, Bombay, have established the use of plutonium as fuel for this reactor. This molten salt reactor concept is described and the work conducted at the Bhabha Atomic Research Centre is summarised. (auth.)

  15. Outgassing From Open And Closed Magma Foams

    Science.gov (United States)

    von Aulock, Felix W.; Kennedy, Ben M.; Maksimenko, Anton; Wadsworth, Fabian B.; Lavallée, Yan

    2017-06-01

    During magma ascent, bubbles nucleate, grow, coalesce, and form a variably permeable porous network. The volcanic system opens and closes as bubble walls reorganize, seal or fail. In this contribution we cause obsidian to nucleate and grow bubbles to high gas volume fraction at atmospheric pressure by heating samples to 950 ºC for different times and we image the growth through a furnace. Following the experiment, we imaged the internal pore structure of selected samples in 3D and then dissected for analysis of textures and dissolved water content remnant in the glass. We demonstrate that in these high viscosity systems, during foaming and subsequent foam-maturation, bubbles near a free surface resorb via diffusion to produce an impermeable skin of melt around a foam. The skin thickens nonlinearly through time. The water concentrations at the outer and inner skin margins reflect the solubility of water in the melt at the partial pressure of water in atmospheric and water-rich bubble conditions, respectively. In this regime, mass transfer of water out of the system is diffusion limited and the sample shrinks slowly. In a second set of experiments in which we polished off the skin of the foamed samples and placed them back in the furnace, we observe rapid sample contraction and collapse of the connected pore network under surface tension as the system efficiently outgasses. In this regime, mass transfer of water is permeability limited. The mechanisms described here are relevant to the evolution of pore network heterogeneity in permeable magmas. We conclude that diffusion-driven skin formation can efficiently seal connectivity in foams. When rupture of melt film around gas bubbles (i.e. skin removal) occurs, then rapid outgassing and consequent foam collapse modulate gas pressurisation in the vesiculated magma.

  16. Outgassing from Open and Closed Magma Foams

    Directory of Open Access Journals (Sweden)

    Felix W. von Aulock

    2017-06-01

    Full Text Available During magma ascent, bubbles nucleate, grow, coalesce, and form a variably permeable porous network. The reorganization, failing and sealing of bubble walls may contribute to the opening and closing of the volcanic system. In this contribution we cause obsidian to nucleate and grow bubbles to high gas volume fraction at atmospheric pressure by heating samples to 950°C for different times and we image the growth through a furnace. Following the experiment, we imaged the internal pore structure of selected samples in 3D and then dissected for analysis of textures and dissolved water content remnant in the glass. We demonstrate that in these high viscosity systems, during foaming and subsequent foam-maturation, bubbles near a free surface resorb via diffusion to produce an impermeable skin of melt around a foam. The skin thickens non-linearly through time. The water concentrations at the outer and inner skin margins reflect the solubility of water in the melt at the partial pressure of water in atmospheric and water-rich bubble conditions, respectively. In this regime, mass transfer of water out of the system is diffusion limited and the sample shrinks slowly. In a second set of experiments in which we polished off the skin of the foamed samples and placed them back in the furnace to allow open system outgassing, we observe rapid sample contraction and collapse of the connected pore network under surface tension as the system efficiently outgasses. In this regime, mass transfer of water is permeability limited. We conclude that diffusion-driven skin formation can efficiently seal connectivity in foams. When rupture of melt film around gas bubbles (i.e., skin removal occurs, then rapid outgassing and consequent foam collapse modulate gas pressurization in the vesiculated magma. The mechanisms described here are relevant to the evolution of pore network heterogeneity in permeable magmas.

  17. Terrestrial magma ocean and core segregation in the earth

    Science.gov (United States)

    Ohtani, Eiji; Yurimoto, Naoyoshi

    1992-01-01

    According to the recent theories of formation of the earth, the outer layer of the proto-earth was molten and the terrestrial magma ocean was formed when its radius exceeded 3000 km. Core formation should have started in this magma ocean stage, since segregation of metallic iron occurs effectively by melting of the proto-earth. Therefore, interactions between magma, mantle minerals, and metallic iron in the magma ocean stage controlled the geochemistry of the mantle and core. We have studied the partitioning behaviors of elements into the silicate melt, high pressure minerals, and metallic iron under the deep upper mantle and lower mantle conditions. We employed the multi-anvil apparatus for preparing the equilibrating samples in the ranges from 16 to 27 GPa and 1700-2400 C. Both the electron probe microanalyzer (EPMA) and the Secondary Ion Mass spectrometer (SIMS) were used for analyzing the run products. We obtained the partition coefficients of various trace elements between majorite, Mg-perovskite, and liquid, and magnesiowustite, Mg-perovskite, and metallic iron. The examples of the partition coefficients of some key elements are summarized in figures, together with the previous data. We may be able to assess the origin of the mantle abundances of the elements such as transition metals by using the partitioning data obtained above. The mantle abundances of some transition metals expected by the core-mantle equilibrium under the lower mantle conditions cannot explain the observed abundance of some elements such as Mn and Ge in the mantle. Estimations of the densities of the ultrabasic magma Mg-perovskite at high pressure suggest existence of a density crossover in the deep lower mantle; flotation of Mg-perovskite occurs in the deep magma ocean under the lower mantle conditions. The observed depletion of some transition metals such as V, Cr, Mn, Fe, Co, and Ni in the mantle may be explained by the two stage process, the core-mantle equilibrium under the lower

  18. On a classification of central Eruptions according to Gas Pressure of the Magma and Viscosity of the Lava

    NARCIS (Netherlands)

    Escher, B.G.

    1933-01-01

    In the above title the word magma is used to signify the solution plus the gas disolved in it under pressure and the word lava for the magma that has partially or entirety lost its content of gas. A clear differentiation of the types of eruptions is not easy, because the character of an eruption

  19. Molten salt reactor type

    International Nuclear Information System (INIS)

    1977-01-01

    This document is one of the three parts of a first volume devoted to the compilations of American data on the molten salt reactor concept. This part describes the MSBR core (data presented are from ORNL 4541). The principal characteristics of the core are presented in tables together with plane and elevation drawings, stress being put upon the reflector, and loading and unloading. Neutronic, and thermal and hydraulic characteristics (core and reflectors) are more detailed. The reasons why a graphite with a tight graphite layer has been chosen are briefly exposed. The physical properties of the standard graphite (irradiation behavior) have been determined for an isotropic graphite with fine granulometry; its dimensional variations largely ressemble that of Gilsonite. The mechanical stresses computed (Wigner effect) do not implicate in any way the graphite stack [fr

  20. Molten salt reactor type

    International Nuclear Information System (INIS)

    1977-01-01

    This document is one of the three parts of a first volume devoted to the compilations of American data on the molten salt reactor concept. This part 'CIRCUITS' regroups under a condensed form - in French and using international units - the essential information contained in both basic documents of the American project for a molten-salt breeder power plant. This part is only dealing with things relating to the CEA-EDF workshop 'CIRCUITS'. It is not concerned with information on: the reactor and the moderator replacement, the primary and secondary salts, and the fuel salt reprocessing, that are dealt with in parts 'CORE' and 'CHEMISTRY' respectively. The possible evolutions in the data - and solutions - taken by the American designers for their successive projects (1970 to 1972) are shown. The MSBR power plant comprises three successive heat transfer circuits. The primary circuit (Hastelloy N), radioactive and polluted, containing the fuel salt, includes the reactor, pumps and exchangers. The secondary circuit (pipings made of modified Hastelloy N) contaminated in the exchanger, ensures the separation between the fuel and the fluid operating the turbo-alternator. The water-steam circuit feeds the turbine with steam. This steam is produced in the steam generator flowed by the secondary fluid. Some subsidiary circuits (discharge and storage of the primary and secondary salts, ventilation of the primary circuit ...) complete the three principal circuits which are briefly described. All circuits are enclosed inside the controlled-atmosphere building of the nuclear boiler. This building also ensures the biological protection and the mechanical protection against outer aggressions [fr

  1. Experimental interaction of magma and “dirty” coolants

    Science.gov (United States)

    Schipper, C. Ian; White, James D. L.; Zimanowski, Bernd; Büttner, Ralf; Sonder, Ingo; Schmid, Andrea

    2011-03-01

    The presence of water at volcanic vents can have dramatic effects on fragmentation and eruption dynamics, but little is known about how the presence of particulate matter in external water will further alter eruptions. Volcanic edifices are inherently “dirty” places, where particulate matter of multiple origins and grainsizes typically abounds. We present the results of experiments designed to simulate non-explosive interactions between molten basalt and various “coolants,” ranging from homogeneous suspensions of 0 to 30 mass% bentonite clay in pure water, to heterogeneous and/or stratified suspensions including bentonite, sand, synthetic glass beads and/or naturally-sorted pumice. Four types of data are used to characterise the interactions: (1) visual/video observations; (2) grainsize and morphology of resulting particles; (3) heat-transfer data from a network of eight thermocouples; and (4) acoustic data from three force sensors. In homogeneous coolants with ~20% sediment, heat transfer is by forced convection and conduction, and thermal granulation is less efficient, resulting in fewer blocky particles, larger grainsizes, and weaker acoustic signals. Many particles are droplet-shaped or/and “vesicular,” containing bubbles filled with coolant. Both of these particle types indicate significant hydrodynamic magma-coolant mingling, and many of them are rewelded into compound particles. The addition of coarse material to heterogeneous suspensions further slows heat transfer thus reducing thermal granulation, and variable interlocking of large particles prevents efficient hydrodynamic mingling. This results primarily in rewelded melt piles and inefficient distribution of melt and heat throughout the coolant volume. Our results indicate that even modest concentrations of sediment in water will significantly limit heat transfer during non-explosive magma-water interactions. At high concentrations, the dramatic reduction in cooling efficiency and increase in

  2. Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera.

    Science.gov (United States)

    Pappalardo, Lucia; Mastrolorenzo, Giuseppe

    2012-01-01

    In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.

  3. The molten salt reactor adventure

    International Nuclear Information System (INIS)

    MacPherson, H.G.

    1985-01-01

    A personal history of the development of molten salt reactors in the United States is presented. The initial goal was an aircraft propulsion reactor, and a molten fluoride-fueled Aircraft Reactor Experiment was operated at Oak Ridge National Laboratory in 1954. In 1956, the objective shifted to civilian nuclear power, and reactor concepts were developed using a circulating UF 4 -ThF 4 fuel, graphite moderator, and Hastelloy N pressure boundary. The program culminated in the successful operation of the Molten Salt Reactor Experiment in 1965 to 1969. By then the Atomic Energy Commission's goals had shifted to breeder development; the molten salt program supported on-site reprocessing development and study of various reactor arrangements that had potential to breed. Some commercial and foreign interest contributed to the program which, however, was terminated by the government in 1976. The current status of the technology and prospects for revived interest are summarized

  4. Weak solutions of magma equations

    International Nuclear Information System (INIS)

    Krishnan, E.V.

    1999-01-01

    Periodic solutions in terms of Jacobian cosine elliptic functions have been obtained for a set of values of two physical parameters for the magma equation which do not reduce to solitary-wave solutions. It was also obtained solitary-wave solutions for another set of these parameters as an infinite period limit of periodic solutions in terms of Weierstrass and Jacobian elliptic functions

  5. Magma flow through elastic-walled dikes

    NARCIS (Netherlands)

    Bokhove, Onno; Woods, A.W.; de Boer, A

    2005-01-01

    A convection–diffusion model for the averaged flow of a viscous, incompressible magma through an elastic medium is considered. The magma flows through a dike from a magma reservoir to the Earth’s surface; only changes in dike width and velocity over large vertical length scales relative to the

  6. Molten material-containing vessel

    International Nuclear Information System (INIS)

    Akagawa, Katsuhiko

    1998-01-01

    The molten material-containing vessel of the present invention comprises a vessel main body having an entrance opened at the upper end, a lid for closing the entrance, an outer tube having an upper end disposed at the lower surface of the lid, extended downwardly and having an closed lower end and an inner tube disposed coaxially with the outer tube. When a molten material is charged from the entrance to the inside of the vessel main body of the molten material-containing vessel and the entrance is closed by the lid, the outer tube and the inner tube are buried in the molten material in the vessel main body, accordingly, a fluid having its temperature elevated by absorption of the heat of the molten material rises along the inner circumferential surface of the outer tube, abuts against the lower surface of the lid and cooled by exchanging heat with the lid and forms a circulating flow. Since the heat in the molten material is continuously absorbed by the fluid, transferred to the lid and released from the lid to the atmospheric air, heat releasing efficiency can be improved compared with conventional cases. (N.H.)

  7. Molten salt reactor type

    International Nuclear Information System (INIS)

    1977-01-01

    This document is one of the three parts of a first volume devoted to the compilations of American data on the molten salt reactor concept. Emphasize is put essentially on the fuel salt of the primary circuit inside which fission reactions occur. The reasons why the (LiF-BeF 2 -ThF 4 -UF 4 ) salt was chosen for the M.S.B.R. concept are examined; the physical, physicochemical and chemical properties of this salt are discussed with its interactions with the structural materials and its evolution in time. An important part of this volume is devoted to the continuous reprocessing of the active salt, the project designers having deemed advisable to take advantage at best from the availability of a continuous purification, in a thermal breeding. The problem of tritium formation and distribution inside the reactor is also envisaged and the fundamentals of the chemistry of the secondary coolant salt are given. The solutions proposed are: the hydrogen scavenging of the primary circuit, a reduction in metal permeability by an oxyde layer deposition on the side in contact with the vapor, and tritium absorption through an isotope exchange with the hydroxifluoroborate [fr

  8. Measurement and Analysis of Density of Molten Ni-W Alloys

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; XIAO Feng; TAO Zainan; MuKai Kusuhiro

    2005-01-01

    The density of molten Ni-W alloys was measured with a modified pycnometric method. It is found that the density of the molten Ni- W alloys decreases with temperature rising, but increases with the increase of tungsten concentration in the alloys. The molar volume of molten Ni- W binary alloys increases with the increase of temperature and tungsten concentration. The partial molar volume of tungsten in liquid Ni- W binary alloy has been calculated approximately as ( - 1.59+ 5.64 × 10-3 T) × 10-6m3 ·mol-1.

  9. Caldera resurgence driven by magma viscosity contrasts.

    Science.gov (United States)

    Galetto, Federico; Acocella, Valerio; Caricchi, Luca

    2017-11-24

    Calderas are impressive volcanic depressions commonly produced by major eruptions. Equally impressive is the uplift of the caldera floor that may follow, dubbed caldera resurgence, resulting from magma accumulation and accompanied by minor eruptions. Why magma accumulates, driving resurgence instead of feeding large eruptions, is one of the least understood processes in volcanology. Here we use thermal and experimental models to define the conditions promoting resurgence. Thermal modelling suggests that a magma reservoir develops a growing transition zone with relatively low viscosity contrast with respect to any newly injected magma. Experiments show that this viscosity contrast provides a rheological barrier, impeding the propagation through dikes of the new injected magma, which stagnates and promotes resurgence. In explaining resurgence and its related features, we provide the theoretical background to account for the transition from magma eruption to accumulation, which is essential not only to develop resurgence, but also large magma reservoirs.

  10. Structure and dynamic properties on molten cuprous halides

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Shin' ichi [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu Chuo-ku, Fukuoka 810 8560 (Japan)]. E-mail: takeda@rc.kyushu-u.ac.jp; Fujii, Hiroyuki [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu Chuo-ku, Fukuoka 810 8560 (Japan); Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto Mikazuki-cho, Sayo-gun, Hyogo 679 5198 (Japan); Kawakita, Yukinobu [Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu Chuo-ku, Fukuoka 810 8560 (Japan); Kato, Yasuhiko [Graduate School of Sciences, Kyushu University, 4-2-1 Ropponmatsu Chuo-ku, Fukuoka 810 8560 (Japan); Kohara, Sinji [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto Mikazuki-cho, Sayo-gun, Hyogo 679 5198 (Japan); Maruyama, Kenji [Department of Chemistry, Faculty of Science, 8050 Igarashi 2, Niigata University, Niigata 950 2181 (Japan)

    2006-11-15

    Neutron and X-ray diffraction measurements have been carried out for molten CuI at 650 deg. C. Both structure factors have been obtained in the wavenumber region beyond 20 A{sup -1}. The three partial structure factors and partial correlation functions have been derived from them with the aid of Reverse Monte Carlo analysis. The Cu-Cu correlation function has the first peak at 2.7 A penetrating into the first coordination shell of Cu-I correlation and a structureless tail, while the I-I correlation exibits long-range oscillations behind the first peak located around 4.35 A. The atomic arrangements for molten CuI are visualized in the figures.

  11. Structure of partly quenched molten copper chloride

    International Nuclear Information System (INIS)

    Pastore, G.; Tosi, M.P.

    1995-09-01

    The structural modifications induced in a model of molten CuCl by quenching the chlorine component into a microporous disordered matrix are evaluated using the hypernetted-chain closure in Ornstein-Zernike relations for the pair distribution functions in random systems. Aside from obvious changes in the behaviour of long-wavelength density fluctuations, the main effect of partial quenching is an enhanced delocalization of the Cu + ions. The model suggests that the ionic mobility in a superionic glass is enhanced relative to the melt at the same temperature and density. Only very minor quantitative differences are found in the structural functions when the replica Ornstein-Zernike relations derived by Given and Stell for a partly quenched system are simplified to those given earlier by Madden and Glandt. (author). 19 refs, 6 figs

  12. Molten fuel-moderator interaction

    International Nuclear Information System (INIS)

    Lee, J.H.S.; Kynstautas, R.

    1987-02-01

    A critical review of the current understanding of vapor explosions was carried out. It was concluded that, on the basis of actual industrial accidents and large scale experiments, energetic high yield steam explosion cannot be regarded as an improbable event if large quantities of molten fuel and coolant are mixed together. This study also reviewed a hydrodynamic transient model proposed by Henry and Fauske Associates to assess a molten fuel-moderator interaction event. It was found that the proposed model negates a priori the possibility of a violent event, by introducing two assumptions: 1) fine fragmentation of the molten fuel, and ii) rapid heat transfer from the fine fragments to form steam. Using the Hicks and Menzies thermodynamic model, maximum work potential and pressure rise in the calandria were estimated. However, it is recommended that a more representative upper bound model based on an underwater explosion of a pressurized volume of steam be developed

  13. Ceramics for Molten Materials Transfer

    Science.gov (United States)

    Standish, Evan; Stefanescu, Doru M.; Curreri, Peter A.

    2009-01-01

    The paper reviews the main issues associated with molten materials transfer and handling on the lunar surface during the operation of a hig h temperature electrowinning cell used to produce oxygen, with molten iron and silicon as byproducts. A combination of existing technolog ies and purposely designed technologies show promise for lunar exploi tation. An important limitation that requires extensive investigation is the performance of refractory currently used for the purpose of m olten metal containment and transfer in the lunar environment associa ted with electrolytic cells. The principles of a laboratory scale uni t at a scale equivalent to the production of 1 metric ton of oxygen p er year are introduced. This implies a mass of molten materials to be transferred consistent with the equivalent of 1kg regolithlhr proces sed.

  14. Aluminum titanate crucible for molten uranium

    International Nuclear Information System (INIS)

    Asbury, J.J.

    1975-01-01

    An improved crucible for molten uranium is described. The crucible or crucible liner is formed of aluminum titanate which essentially eliminates contamination of uranium and uranium alloys during molten states thereof. (U.S.)

  15. Drilling into Rhyolitic Magma at Shallow depth at Krafla Volcanic Complex, NE-Iceland

    Science.gov (United States)

    Mortensen, A. K.; Markússon, S. H.; Gudmundsson, Á.; Pálsson, B.

    2017-12-01

    Krafla volcanic complex in NE-Iceland is an active volcano but the latest eruption was the Krafla Fires in 1975-1984. Though recent volcanic activity has consisted of basaltic fissure eruptions, then it is rhyolitic magma that has been intercepted on at least two occasions while drilling geothermal production wells in the geothermal field suggesting a layered magma plumbing system beneath the Krafla volcanic complex. In 2008 quenched rhyolitic glass was retrieved from the bottom of well KJ-39, which is 2865 m deep ( 2571 m true vertical depth). In 2009 magma was again encountered at an even shallower depth and in more than 2,5 km distance from the bottom of well KJ-39, but in 2009 well IDDP-1 was drilled into magma three times just below 2100 m depth. Only on the last occasion was quenched glass retrieved to confirm that magma had been encountered. In well KJ-39 the quenched glass was rhyolitic in composition. The glass contained resorbed minerals of plagioclase, clinopyroxene and titanomagnetite, but the composition of the glass resembles magma that has formed by partial melting of hydrated basalt. The melt was encountered among cuttings from impermeable, coarse basaltic intrusives at a depth, where the well was anticipated to penetrate the Hólseldar volcanic fissure. In IDDP-1 the quenched glass was also rhyolitic in composition. The glass contained less than 5% of phenocrysts, but the phenocryst assemblage included andesine plagioclase, augite, pigeonite, and titanomagnetite. At IDDP-1 the melt was encountered below a permeable zone composed of fine to coarse grained felsite and granophyre. The disclosure of magma in two wells at Krafla volcanic complex verify that rhyolitic magma can be encountered at shallow depth across a larger area within the caldera. The encounter of magma at shallow depth conforms with that superheated conditions have been found at >2000 m depth in large parts of Krafla geothermal field.

  16. Interaction of coeval felsic and mafic magmas from the Kanker ...

    Indian Academy of Sciences (India)

    66

    20 crystallization of the latter, results in hybrid magmas under the influence of thermal and. 21 chemical exchange. The mechanical exchange occurs between the coexisting magmas due to. 22 viscosity contrast, if the mafic magma enters slightly later into the magma chamber, when the. 23 felsic magma started to crystallize.

  17. Catalysis in Molten Ionic Media

    DEFF Research Database (Denmark)

    Boghosian, Soghomon; Fehrmann, Rasmus

    2013-01-01

    This chapter deals with catalysis in molten salts and ionic liquids, which are introduced and reviewed briefly, while an in-depth review of the oxidation catalyst used for the manufacturing of sulfuric acid and cleaning of flue gas from electrical power plants is the main topic of the chapter...

  18. thermic oil and molten salt

    African Journals Online (AJOL)

    Boukelia T.E, Mecibah M.S and Laouafi A

    1 mai 2016 ... [27] Zavoico, AB. Solar Power Tower Design Basis Document. Tech. rep, Sandia National. Laboratories, SAND2001-2100, 2001. How to cite this article: Boukelia T.E, Mecibah M.S and Laouafi A. Performance simulation of parabolic trough solar collector using two fluids (thermic oil and molten salt).

  19. Origin of silicic magmas along the Central American volcanic front: Genetic relationship to mafic melts

    Science.gov (United States)

    Vogel, Thomas A.; Patino, Lina C.; Eaton, Jonathon K.; Valley, John W.; Rose, William I.; Alvarado, Guillermo E.; Viray, Ela L.

    2006-09-01

    Silicic pyroclastic flows and related deposits are abundant along the Central American volcanic front. These silicic magmas erupted through both the non-continental Chorotega block to the southeast and the Paleozoic continental Chortis block to the northwest. The along-arc variations of the silicic deposits with respect to diagnostic trace element ratios (Ba/La, U/Th, Ce/Pb), oxygen isotopes, Nd and Sr isotope ratios mimic the along-arc variation in the basaltic and andesitic lavas. This variation in the lavas has been interpreted to indicate relative contributions from the slab and asthenosphere to the basaltic magmas [Carr, M.J., Feigenson, M.D., Bennett, E.A., 1990. Incompatible element and isotopic evidence for tectonic control of source mixing and melt extraction along the Central American arc. Contributions to Mineralogy and Petrology, 105, 369-380.; Patino, L.C., Carr, M.J. and Feigenson, M.D., 2000. Local and regional variations in Central American arc lavas controlled by variations in subducted sediment input. Contributions to Mineralogy and Petrology, 138 (3), 265-283.]. With respect to along-arc trends in basaltic lavas the largest contribution of slab fluids is in Nicaragua and the smallest input from the slab is in central Costa Rica — similar trends are observed in the silicic pyroclastic deposits. Data from melting experiments of primitive basalts and basaltic andesites demonstrate that it is difficult to produce high K 2O/Na 2O silicic magmas by fractional crystallization or partial melting of low-K 2O/Na 2O sources. However fractional crystallization or partial melting of medium- to high-K basalts can produce these silicic magmas. We interpret that the high-silica magmas associated Central America volcanic front are partial melts of penecontemporaneous, mantle-derived, evolved magmas that have ponded and crystallized in the mid-crust — or are melts extracted from these nearly completely crystallized magmas.

  20. Saturated steams pressure of HfCl/sub 4/-KCl molten mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, A B; Smirnov, M V; Kudyakov, V Ya [AN SSSR, Sverdlovsk. Inst. Ehlektrokhimii

    1980-02-01

    A bellows null pressure gauge and the dynamic method were used to measure the total and partial pressures of saturated vapors of individual components of molten HfCl/sub 4/-KCl mixtures, as a function of temperature (260 to 1000 deg C) and composition (1.9 to 64.3 mol.% HfCl/sub 4/). Empirical equations expressing the relationship between pressure and temperature are presented. It is shown that in molten mixtures of hafnium tetrachloride with chlorides of alkaline metals its partial pressure dramatically increases when potassium chloride substitutes for cesium chloride.

  1. Saturated steams pressure of HfCl4-KCl molten mixtures

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Smirnov, M.V.; Kudyakov, V.Ya.

    1980-01-01

    A bellows null pressure gauge and the dynamic method were used to measure the total and partial pressures of saturated vapors of individual components of molten HfCl 4 -KCl mixtures, as a function of temperature (260 to 1000 deg C) and composition (1.9 to 64.3 mol.% HfCl 4 ). Empirical equations expressing the relationship between pressure and temperature are presented. It is shown that in molten mixtures of hafnium tetrachloride with chlorides of alkaline metals its partial pressure dramatically increases when potassium chloride substitutes for cesium chloride

  2. Magma mixing in granitic rocks of the central Sierra Nevada, California

    Science.gov (United States)

    Reid, John B.; Evans, Owen C.; Fates, Dailey G.

    1983-12-01

    The El Capitan alaskite exposed in the North American Wall, Yosemite National Park, was intruded by two sets of mafic dikes that interacted thermally and chemically with the host alaskite. Comparisons of petrographic and compositional data for these dikes and alaskite with published data for Sierra Nevada plutons lead us to suggest that mafic magmas were important in the generation of the Sierra Nevada batholith. Specifically, we conclude that: (1) intrusion of mafic magmas in the lower crust caused partial melting and generation of alaskite (rhyolitic) magmas; (2) interaction between the mafic and felsic magmas lead to the observed linear variation diagrams for major elements; (3) most mafic inclusions in Sierra Nevada plutons represent chilled pillows of mafic magmas, related by fractional crystallization and granitoid assimilation, that dissolve into their felsic host and contaminate it to intermediate (granodioritic) compositions; (4) vesiculation of hydrous mafic magma upon chilling may allow buoyant mafic inclusions and their disaggregation products to collect beneath a pluton's domed ceiling causing the zoning (mafic margins-to-felsic core) that these plutons exhibit.

  3. Temperatures and isotopic evolution of silicic magmas, Taupo Volcanic Zone and Coromandel, New Zealand

    International Nuclear Information System (INIS)

    Blattner, P.; Rui-Zhong H.; Graham, I.J.; Houston-Eleftheriadis, C.

    1996-01-01

    A new set of oxygen and strontium isotope data on rhyolitic lavas and ignimbrites of the Taupo Volcanic Zone (TVZ) and the Coromandel Peninsula provides new limits for petrogenic models. For oxygen isotopes, the rock matrix is frequently altered, so that values for magma need to be phenocryst based. Within TVZ a trend towards more negative δ 1 8O values for more recent magmas appears likely (average before about 1 Ma and for Coromandel near 8.0 per mille; after 1 Ma near 7.5 per mille). This could indicate the gradual removal of supracrustal contaminants from the zones of magma accumulation and extrusion. Similar trends within Coromandel cannot yet be resolved. A generally positive correlation is found for oxygen and strontium isotopes of magmas. Most magmas have a limited range of isotopic values, which then becomes a fingerprint (e.g., the Mamaku, Matahina, and Waiotapu Ignimbrites). A narrow range of eruption temperatures of 880 ± 60 o C is derived from quartz-plagioclase fractionations of 0.98 ± 0.25 per mille δ 1 8O values of quartz and feldspar phenocrysts are sufficiently low to suggest interaction between surface water and magma. However, large negative oxygen isotope anomalies (such as known from Yellowstone), could be no more than partially concealed by the isotopically less depleted meteoric water of New Zealand, and have not yet been found in New Zealand. (authors). 45 refs., 6 figs., 3 tabs

  4. Trace element and isotopic effects arising from magma migration beneath mid-ocean ridges

    International Nuclear Information System (INIS)

    Kenyon, P.M.

    1990-01-01

    The trace element concentrations and isotopic ratios in the magma erupted on mid-ocean ridges may differ from those in the source material due to physical effects such as porous flow dispersion, exchange of trace elements between the fluid and solid phases during magma migration, and convective mixing in magma chambers. These differences are in addition to those produced by better known processes such as fractional crystallization and partial melting. The effects of the three former processes are described. It is predicted that magma typically reaches the sub-ridge magma chambers with a spatial heterogeneity only slightly reduced from that of the source material, but with a subdued variation in time. Convective mixing then further reduces the spatial heterogeneity. Application of the results for convective mixing to a recent Fourier analysis of 87 Sr/ 86 Sr variations along the Mid-Atlantic Ridge suggests that the falloff in amplitude of variation observed with decreasing wavelength in the Mid-Atlantic Ridge data cannot be explained by convective mixing in magma chambers. Instead, it is postulated that this falloff is due to the mechanics of the production and/or the solid-state convective mixing of chemical and isotopic heterogeneities in the solid mantle. (orig.)

  5. Depth of origin of magma in eruptions.

    Science.gov (United States)

    Becerril, Laura; Galindo, Ines; Gudmundsson, Agust; Morales, Jose Maria

    2013-09-26

    Many volcanic hazard factors--such as the likelihood and duration of an eruption, the eruption style, and the probability of its triggering large landslides or caldera collapses--relate to the depth of the magma source. Yet, the magma source depths are commonly poorly known, even in frequently erupting volcanoes such as Hekla in Iceland and Etna in Italy. Here we show how the length-thickness ratios of feeder dykes can be used to estimate the depth to the source magma chamber. Using this method, accurately measured volcanic fissures/feeder-dykes in El Hierro (Canary Islands) indicate a source depth of 11-15 km, which coincides with the main cloud of earthquake foci surrounding the magma chamber associated with the 2011-2012 eruption of El Hierro. The method can be used on widely available GPS and InSAR data to calculate the depths to the source magma chambers of active volcanoes worldwide.

  6. Volcanic emission of radionuclides and magma dynamics

    International Nuclear Information System (INIS)

    Lambert, G.; Le Cloarec, M.F.; Ardouin, B.; Le Roulley, J.C.

    1985-01-01

    210 Pb, 210 Bi and 210 Po, the last decay products of the 238 U series, are highly enriched in volcanic plumes, relative to the magma composition. Moreover this enrichment varies over time and from volcano to volcano. A model is proposed to describe 8 years of measurements of Mt. Etna gaseous emissions. The lead and bismuth coefficients of partition between gaseous and condensated phases in the magma are determined by comparing their concentrations in lava flows and condensated volatiles. In the case of volatile radionuclides, an escaping time is calculated which appears to be related to the volcanic activity. Finally, it is shown that that magma which is degassing can already be partly degassed; it should be considered as a mixture of a few to 50% of deep non-degassed magma with a well degassed superficial magma cell. (orig.)

  7. Shear thinning behaviors in magmas

    Science.gov (United States)

    Vetere, F. P.; Cassetta, M.; Perugini, D.

    2017-12-01

    Studies on magma rheology are of fundamental importance to understanding magmatic processes from depth to surface. Since viscosity is one of the most important parameter controlling eruption mechanisms, as well as lava flow emplacement, a comprehensive knowledge on the evolution of magma viscosities during crystallization is required. We present new viscosity data on partly crystalized basalt, andesite and analogue lavas comparable to those erupted on Mercury's northern volcanic plains. High-temperature viscosity measurements were performed using a rotational Anton Paar RheolabQC viscometer head at the PVRG labs, in Perugia (Italy) (http://pvrg.unipg.it). The relative proportion of phases in each experimental run were determined by image analysis on BS-SEM images at different magnifications; phases are glasses, clinopyroxene, spinel, plagioclase for the basalt, plagioclase and spinel for the andesite and pure enstatite and clinopyroxenes, for the analogue Mercury's composition. Glass and crystalline fractions determined by image analysis well correlate with compositions of residual melts. In order to constrain the viscosity (η) variations as a function of crystallinity, shear rate (γ) was varied from 0.1 to 5 s-1. Viscosity vs. time at constant temperature shows a typical S-shape curve. In particular, for basaltic composition η vary from 3.1-3.8 Pa s [log η] at 1493 K and crystallinity of 19 area % as γ vary from 1.0 to 0.1 s-1; the andesite viscosity evolution is 3.2 and 3.7 Pa s [log η] as γ varies from 1 to 0.1 at 1493 K and crystal content of 17 area %; finally, Mercury's analogue composition was investigated at different temperature ranging from 1533 to 1502 K (Vetere et al., 2017). Results, for γ = 0.1, 1.0 and 5.0 s-1, show viscosity variation between 2.7-4.0, 2.5-3.4 and 2.0-3.0 [log η inPa s] respectively while crystallinity vary from 9 to 27 (area %). As viscosity decreases as shear rate increases, these data points to a shear thinning behaviour

  8. Accelerator molten-salt breeder reactor

    International Nuclear Information System (INIS)

    Furukawa, Kazuo; Kuroi, Hideo; Kato, Yoshio; Oomichi, Toshihiko.

    1979-01-01

    Purpose: To obtain fission products and to transmute transuranium elements and other radioactive wastes by the use of Accelerator Molten-Salt Breeder Reactor. Constitution: Beams from an accelerator pipe at one end of a target vessel is injected through a window into target molten salts filled inside of the target vessel. The target molten salts are subjected to pump recycling or spontaneous convection while forcively cooled by blanket molten salts in an outer vessel. Then, energy is recovered from the blanket molten salts or the target molten salts at high temperatures through electric power generation or the like. Those salts containing such as thorium 232 and uranium 238 are used as the blanket molten salts so that fission products may be produced by neutrons generated in the target molten salts. PbCl 2 -PbF 2 and LiF-BeF 2 -ThF 4 can be used as the target molten salts and as the blanket molten salts respectively. (Seki, T.)

  9. Heterogeneity in lunar anorthosite meteorites: implications for the lunar magma ocean model.

    Science.gov (United States)

    Russell, Sara S; Joy, Katherine H; Jeffries, Teresa E; Consolmagno, Guy J; Kearsley, Anton

    2014-09-13

    The lunar magma ocean model is a well-established theory of the early evolution of the Moon. By this model, the Moon was initially largely molten and the anorthositic crust that now covers much of the lunar surface directly crystallized from this enormous magma source. We are undertaking a study of the geochemical characteristics of anorthosites from lunar meteorites to test this model. Rare earth and other element abundances have been measured in situ in relict anorthosite clasts from two feldspathic lunar meteorites: Dhofar 908 and Dhofar 081. The rare earth elements were present in abundances of approximately 0.1 to approximately 10× chondritic (CI) abundance. Every plagioclase exhibited a positive Eu-anomaly, with Eu abundances of up to approximately 20×CI. Calculations of the melt in equilibrium with anorthite show that it apparently crystallized from a magma that was unfractionated with respect to rare earth elements and ranged in abundance from 8 to 80×CI. Comparisons of our data with other lunar meteorites and Apollo samples suggest that there is notable heterogeneity in the trace element abundances of lunar anorthosites, suggesting these samples did not all crystallize from a common magma source. Compositional and isotopic data from other authors also suggest that lunar anorthosites are chemically heterogeneous and have a wide range of ages. These observations may support other models of crust formation on the Moon or suggest that there are complexities in the lunar magma ocean scenario to allow for multiple generations of anorthosite formation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Numerical modeling of bubble dynamics in magmas

    Science.gov (United States)

    Huber, Christian; Su, Yanqing; Parmigiani, Andrea

    2014-05-01

    Understanding the complex non-linear physics that governs volcanic eruptions is contingent on our ability to characterize the dynamics of bubbles and its effect on the ascending magma. The exsolution and migration of bubbles has also a great impact on the heat and mass transport in and out of magma bodies stored at shallow depths in the crust. Multiphase systems like magmas are by definition heterogeneous at small scales. Although mixture theory or homogenization methods are convenient to represent multiphase systems as a homogeneous equivalent media, these approaches do not inform us on possible feedbacks at the pore-scale and can be significantly misleading. In this presentation, we discuss the development and application of bubble-scale multiphase flow modeling to address the following questions : How do bubbles impact heat and mass transport in magma chambers ? How efficient are chemical exchanges between the melt and bubbles during magma decompression? What is the role of hydrodynamic interactions on the deformation of bubbles while the magma is sheared? Addressing these questions requires powerful numerical methods that accurately model the balance between viscous, capillary and pressure stresses. We discuss how these bubble-scale models can provide important constraints on the dynamics of magmas stored at shallow depth or ascending to the surface during an eruption.

  11. Evidence for seismogenic fracture of silicic magma.

    Science.gov (United States)

    Tuffen, Hugh; Smith, Rosanna; Sammonds, Peter R

    2008-05-22

    It has long been assumed that seismogenic faulting is confined to cool, brittle rocks, with a temperature upper limit of approximately 600 degrees C (ref. 1). This thinking underpins our understanding of volcanic earthquakes, which are assumed to occur in cold rocks surrounding moving magma. However, the recent discovery of abundant brittle-ductile fault textures in silicic lavas has led to the counter-intuitive hypothesis that seismic events may be triggered by fracture and faulting within the erupting magma itself. This hypothesis is supported by recent observations of growing lava domes, where microearthquake swarms have coincided with the emplacement of gouge-covered lava spines, leading to models of seismogenic stick-slip along shallow shear zones in the magma. But can fracturing or faulting in high-temperature, eruptible magma really generate measurable seismic events? Here we deform high-temperature silica-rich magmas under simulated volcanic conditions in order to test the hypothesis that high-temperature magma fracture is seismogenic. The acoustic emissions recorded during experiments show that seismogenic rupture may occur in both crystal-rich and crystal-free silicic magmas at eruptive temperatures, extending the range of known conditions for seismogenic faulting.

  12. Examining shear processes during magma ascent

    Science.gov (United States)

    Kendrick, J. E.; Wallace, P. A.; Coats, R.; Lamur, A.; Lavallée, Y.

    2017-12-01

    Lava dome eruptions are prone to rapid shifts from effusive to explosive behaviour which reflects the rheology of magma. Magma rheology is governed by composition, porosity and crystal content, which during ascent evolves to yield a rock-like, viscous suspension in the upper conduit. Geophysical monitoring, laboratory experiments and detailed field studies offer the opportunity to explore the complexities associated with the ascent and eruption of such magmas, which rest at a pivotal position with regard to the glass transition, allowing them to either flow or fracture. Crystal interaction during flow results in strain-partitioning and shear-thinning behaviour of the suspension. In a conduit, such characteristics favour the formation of localised shear zones as strain is concentrated along conduit margins, where magma can rupture and heal in repetitive cycles. Sheared magmas often record a history of deformation in the form of: grain size reduction; anisotropic permeable fluid pathways; mineral reactions; injection features; recrystallisation; and magnetic anomalies, providing a signature of the repetitive earthquakes often observed during lava dome eruptions. The repetitive fracture of magma at ( fixed) depth in the conduit and the fault-like products exhumed at spine surfaces indicate that the last hundreds of meters of ascent may be controlled by frictional slip. Experiments on a low-to-high velocity rotary shear apparatus indicate that shear stress on a slip plane is highly velocity dependent, and here we examine how this influences magma ascent and its characteristic geophysical signals.

  13. Thermal performances of molten salt steam generator

    International Nuclear Information System (INIS)

    Yuan, Yibo; He, Canming; Lu, Jianfeng; Ding, Jing

    2016-01-01

    Highlights: • Thermal performances of molten salt steam generator were experimentally studied. • Overall heat transfer coefficient reached maximum with optimal molten salt flow rate. • Energy efficiency first rose and then decreased with salt flow rate and temperature. • Optimal molten salt flow rate and temperature existed for good thermal performance. • High inlet water temperature benefited steam generating rate and energy efficiency. - Abstract: Molten salt steam generator is the key technology for thermal energy conversion from high temperature molten salt to steam, and it is used in solar thermal power station and molten salt reactor. A shell and tube type molten salt steam generator was set up, and its thermal performance and heat transfer mechanism were studied. As a coupling heat transfer process, molten salt steam generation is mainly affected by molten salt convective heat transfer and boiling heat transfer, while its energy efficiency is also affected by the heat loss. As molten salt temperature increased, the energy efficiency first rose with the increase of heat flow absorbed by water/steam, and then slightly decreased for large heat loss as the absorbed heat flow still rising. At very high molten salt temperature, the absorbed heat flow decreased as boiling heat transfer coefficient dropping, and then the energy efficiency quickly dropped. As the inlet water temperature increased, the boiling region in the steam generator remarkably expanded, and then the steam generation rate and energy efficiency both rose with the overall heat transfer coefficient increasing. As the molten salt flow rate increased, the wall temperature rose and the boiling heat transfer coefficient first increased and then decreased according to the boiling curve, so the overall heat transfer coefficient first increased and then decreased, and then the steam generation rate and energy efficiency of steam generator both had maxima.

  14. Pore Scale Thermal Hydraulics Investigations of Molten Salt Cooled Pebble Bed High Temperature Reactor with BCC and FCC Configurations

    Directory of Open Access Journals (Sweden)

    Shixiong Song

    2014-01-01

    CFD results and empirical correlations’ predictions of pressure drop and local Nusselt numbers. Local pebble surface temperature distributions in several default conditions are investigated. Thermal removal capacities of molten salt are confirmed in the case of nominal condition; the pebble surface temperature under the condition of local power distortion shows the tolerance of pebble in extreme neutron dose exposure. The numerical experiments of local pebble insufficient cooling indicate that in the molten salt cooled pebble bed reactor, the pebble surface temperature is not very sensitive to loss of partial coolant. The methods and results of this paper would be useful for optimum designs and safety analysis of molten salt cooled pebble bed reactors.

  15. Magma Mixing: Why Picrites are Not So Hot

    Science.gov (United States)

    Natland, J. H.

    2010-12-01

    Oxide gabbros or ferrogabbros are the late, low-temperature differentiates of tholeiitic magma and usually form as cumulates that can have 2-30% of the magmatic oxides, ilmenite and magnetite. They are common in the ocean crust and are likely ubiquitous wherever extensive tholeiitic magmatism has occurred, especially beneath thick lava piles such as at Hawaii, Iceland, oceanic plateaus, island arcs and ancient continental crust. When intruded by hot primitive magma including picrite, the oxide-bearing portions of these rocks are readily partially melted or assimilated into the magma and contribute to it a degree of iron and titanium enrichment that is not reflective of the mantle source of the primitive magma. The most extreme examples of such mixing are meimechites and ferropicrites, but this type of end-member mixing is even common in MORB. To the extent this process occurs, the eruptive picrite cannot be used to estimate compositions of partial melts of mantle rocks, nor their eruptive or potential temperatures, using olivine-liquid FeO-MgO backtrack procedures. Most picrites have glasses with compositions approximating those expected from low-pressure multiphase cotectic crystallization, and olivine that on average crystallized from liquids of nearly those compositions. The hallmark of such rocks is the presence of minerals other than olivine among phenocrysts (plagioclase at Iceland, clinopyroxene at many oceanic islands), Fe- and Ti-rich chromian spinel (ankaramites, ferropicrites and meimichites), and in some cases the presence of iron-rich olivine (hortonolite ~Fo65 in ferropicrites), Ti-rich kaersutitic amphibole and even apatite (meimechites); the latter two derive from late-stage, hydrous and geochemically enriched metamorphic or alkalic assimilants. This type of mixing, however, does not necessarily involve depleted and enriched mixing components. To avoid such mixing, primitive melts have to rise primarily through upper mantle rocks of near-zero melt

  16. The 2006-2009 activity of the Ubinas volcano (Peru): Petrology of the 2006 eruptive products and insights into genesis of andesite magmas, magma recharge and plumbing system

    Science.gov (United States)

    Rivera, Marco; Thouret, Jean-Claude; Samaniego, Pablo; Le Pennec, Jean-Luc

    2014-01-01

    Following a fumarolic episode that started six months earlier, the most recent eruptive activity of the Ubinas volcano (south Peru) began on 27 March 2006, intensified between April and October 2006 and slowly declined until December 2009. The chronology of the explosive episode and the extent and composition of the erupted material are documented with an emphasis on ballistic ejecta. A petrological study of the juvenile products allows us to infer the magmatic processes related to the 2006-2009 eruptions of the andesitic Ubinas volcano. The juvenile magma erupted during the 2006 activity shows a homogeneous bulk-rock andesitic composition (56.7-57.6 wt.% SiO2), which belongs to a medium- to high-K calc-alkaline series. The mineral assemblage of the ballistic blocks and tephra consists of plagioclase > two-pyroxenes > Fe-Ti oxide and rare olivine and amphibole set in a groundmass of the same minerals with a dacitic composition (66-67 wt.% SiO2). Thermo-barometric data, based on two-pyroxene and amphibole stability, records a magma temperature of 998 ± 14 °C and a pressure of 476 ± 36 MPa. Widespread mineralogical and textural features point to a disequilibrium process in the erupted andesite magma. These features include inversely zoned "sieve textures" in plagioclase, inversely zoned clinopyroxene, and olivine crystals with reaction and thin overgrowth rims. They indicate that the pre-eruptive magmatic processes were dominated by recharge of a hotter mafic magma into a shallow reservoir, where magma mingling occurred and triggered the eruption. Prior to 2006, a probable recharge of a mafic magma produced strong convection and partial homogenization in the reservoir, as well as a pressure increase and higher magma ascent rate after four years of fumarolic activity. Mafic magmas do not prevail in the Ubinas pre-historical lavas and tephras. However, mafic andesites have been erupted during historical times (e.g. AD 1667 and 2006-2009 vulcanian eruptions). Hence

  17. CFD to modeling molten core behavior simultaneously with chemical phenomena

    International Nuclear Information System (INIS)

    Vladimir V Chudanov; Anna E Aksenova; Valerii A Pervichko

    2005-01-01

    Full text of publication follows: This paper deals with the basic features of a computing procedure, which can be used for modeling of destruction and melting of a core with subsequent corium retaining into the reactor vessel. The destruction and melting of core mean the account of the following phenomena: a melting, draining (moving of the melt through a porous layer of core debris), freezing with release of an energy, change of geometry, formation of the molten pool, whose convective intermixing and distribution influence on a mechanism of borders destruction. It is necessary to take into account that during of heating molten pool and development in it of convective fluxes a stratification of a multi-component melt on two layers of metal light and of oxide heavy components is observed. These layers are in interaction, they can exchange by the separate components as result of diffusion or oxidizing reactions. It can have an effect considerably on compositions, on a specific weight, and on properties of molten interacting phases, and on a structure of the molten stratified pool. In turn, the retaining of the formed molten masses in reactor vessel requires the solution of a matched heat exchange problem, namely, of a natural convection in a heat generating fluid in partially or completely molten corium and of heat exchange problem with taking into account of a melting of the reactor vessel. In addition, it is necessary to take into account phase segregation, caused by influence of local and of global natural convective flows and thermal lag of heated up boundaries. The mathematical model for simulation of the specified phenomena is based on the Navier-Stokes equations with variable properties together with the heat transfer equation. For modeling of a corium moving through a porous layer of core debris, the special computing algorithm to take into account density jump on interface between a melt and a porous layer of core debris is designed. The model was

  18. Structure and thermodynamic properties of molten alkali chlorides

    International Nuclear Information System (INIS)

    Ballone, P.; Pastore, G.; Tosi, M.P.; Trieste Univ.

    1984-03-01

    Self-consistent calculations of partial pair distribution functions and thermodynamic properties are presented for molten alkali chlorides in a non-polarizable-ion model. The theory starts from the hypernetted chain approximation and analyzes the role of bridge diagrams both for a two-component ionic plasma on a neutralizing background and for a binary ionic liquid of cations and anions. A simple account of excluded-volume effects suffices for a good description of the pair distribution functions in the two-component plasma, in analogy with earlier work on one-component fluids. The interplay of Coulomb attractions and repulsions in the molten salt requires, on the other hand, the inclusion of (i) excluded-volume effects for the various ion pairs as in a mixture of hard spheres with non-additive radii and (ii) medium-range Coulomb effects reflected mainly in the like-ion correlations. All these effects are included approximately in an empirical evaluation of the bridge functions, with numerical results which compare very well with computer simulation data. A detailed discussion of the results against experimental structural data is then given in the case of molten sodium chloride. (author)

  19. Comments on 'Generation of Deccan Trap magmas'

    Indian Academy of Sciences (India)

    R.Narasimhan(krishtel emaging)1461 1996 Oct 15 13:05:22

    Comments on 'Generation of Deccan Trap magmas' by Gautam Sen ... Department of Geology & Geophysics, School of Ocean & Earth Science & Technology (SOEST), University of .... Mahoney J J, Sheth H C, Chandrasekharan D and Peng Z.

  20. The Boycott effect in magma chambers

    Science.gov (United States)

    Blanchette, F.; Peacock, T.; Bush, J. W. M.

    2004-03-01

    We investigate the plausibility of the stratified Boycott effect as a source of layering in magma chambers. Crystal settling within the magma chamber will generate buoyant fluid near the sloping sidewalls whose vertical ascent may be limited by the ambient stratification associated with vertical gradients in SiO2. The resulting flow may be marked by a layered structure, each layer taking the form of a convection cell spanning the lateral extent of the magma chamber. Using parameters relevant to magma chambers, we estimate that such convection cells would be established over a timescale of a month and have a depth on the order of 4m, which is roughly consistent with field observations of strata within solidified chambers.

  1. Magma Chambers, Thermal Energy, and the Unsuccessful Search for a Magma Chamber Thermostat

    Science.gov (United States)

    Glazner, A. F.

    2015-12-01

    Although the traditional concept that plutons are the frozen corpses of huge, highly liquid magma chambers ("big red blobs") is losing favor, the related notion that magma bodies can spend long periods of time (~106years) in a mushy, highly crystalline state is widely accepted. However, analysis of the thermal balance of magmatic systems indicates that it is difficult to maintain a significant portion in a simmering, mushy state, whether or not the system is eutectic-like. Magma bodies cool primarily by loss of heat to the Earth's surface. The balance between cooling via energy loss to the surface and heating via magma accretion can be denoted as M = ρLa/q, where ρ is magma density, L is latent heat of crystallization, a is the vertical rate of magma accretion, and q is surface heat flux. If M>1, then magma accretion outpaces cooling and a magma chamber forms. For reasonable values of ρ, L, and q, the rate of accretion amust be > ~15 mm/yr to form a persistent volume above the solidus. This rate is extremely high, an order of magnitude faster than estimated pluton-filling rates, and would produce a body 10 km thick in 700 ka, an order of magnitude faster than geochronology indicates. Regardless of the rate of magma supply, the proportion of crystals in the system must vary dramatically with depth at any given time owing to transfer of heat. Mechanical stirring (e.g., by convection) could serve to homogenize crystal content in a magma body, but this is unachievable in crystal-rich, locked-up magma. Without convection the lower part of the magma body becomes much hotter than the top—a process familiar to anyone who has scorched a pot of oatmeal. Thermal models that succeed in producing persistent, large bodies of magma rely on scenarios that are unrealistic (e.g., omitting heat loss to the planet's surface), self-fulfilling prophecies (e.g., setting unnaturally high temperatures as fixed boundary conditions), or physically unreasonable (e.g., magma is intruded

  2. Precipitation of lamellar gold nanocrystals in molten polymers

    International Nuclear Information System (INIS)

    Palomba, M.; Carotenuto, G.

    2016-01-01

    Non-aggregated lamellar gold crystals with regular shape (triangles, squares, pentagons, etc.) have been produced by thermal decomposition of gold chloride (AuCl) molecules in molten amorphous polymers (polystyrene and poly(methyl methacrylate)). Such covalent inorganic gold salt is high soluble into non-polar polymers and it thermally decomposes at temperatures compatible with the polymer thermal stability, producing gold atoms and chlorine radicals. At the end of the gold precipitation process, the polymer matrix resulted chemically modified because of the partial cross-linking process due to the gold atom formation reaction.

  3. Large longitude libration of Mercury reveals a molten core.

    Science.gov (United States)

    Margot, J L; Peale, S J; Jurgens, R F; Slade, M A; Holin, I V

    2007-05-04

    Observations of radar speckle patterns tied to the rotation of Mercury establish that the planet occupies a Cassini state with obliquity of 2.11 +/- 0.1 arc minutes. The measurements show that the planet exhibits librations in longitude that are forced at the 88-day orbital period, as predicted by theory. The large amplitude of the oscillations, 35.8 +/- 2 arc seconds, together with the Mariner 10 determination of the gravitational harmonic coefficient C22, indicates that the mantle of Mercury is decoupled from a core that is at least partially molten.

  4. Niobium electrodeposition from molten fluorides

    International Nuclear Information System (INIS)

    Sartori, A.F.

    1987-01-01

    Niobium electrodeposition from molten alkali fluorides has been studied aiming the application of this technic to the processes of electrorefining and galvanotechnic of this metal. The effects of current density, temperature, niobium concentration in the bath, electrolysis time, substrate nature, ratio between anodic and cathodic areas, electrodes separation and the purity of anodes were investigated in relation to the cathodic current efficiency, electrorefining, electroplating and properties of the deposit and the electrolytic solution. The work also gives the results of the conctruction and operation of a pilot plant for refractory metals electrodeposition and shows the electrorefining and electroplating compared to those obtained at the laboratory scale. (author) [pt

  5. Reconciling Gases With Glasses: Magma Degassing, Overturn and Mixing at Kilauea Volcano, Hawai`i

    Science.gov (United States)

    Edmonds, M.; Gerlach, T. M.

    2006-12-01

    Our understanding of the volatile budget at Kilauea Volcano is based on measurements of the abundance of volatile elements in volcanic glasses and gases. Observations of volcanic gases gave rise to a fundamental model describing volatile fractionation between the summit and rift zone during the current eruption [Gerlach and Graeber, 1985]. Other workers' analysis of glasses from the Puna Ridge, Kilauea Iki and Pu`u `O`o indicate that magma degassing, drain-back, mixing and assimilation are important processes at Kilauea Volcano. Volcanic gases have not illustrated these kinds of processes clearly in the past, owing to infrequent and poorly resolved data. New, detailed studies of volcanic gas emissions have refined our understanding of volatile degassing and magma budgets at Kilauea Volcano. Open Path Fourier Transform Infra-Red spectroscopy measurements carried out during 2004-2005 allow retrieval of the relative abundances of the major volatile species H2O, CO2 and SO2, which together make up >99 vol% of the magmatic vapor phase. The proportions of these gases vary over time and space and can be used to infer magma transport, ascent, degassing, overturn and mixing and gas segregation processes within the plumbing system of Kilauea Volcano. Gases from Pu`u `O`o in 2004-2005 display a range in composition. A trend relates molar C/S to the total H2O content of the gases over time and space; total H2O ranges from 60-98 mol %, while molar C/S ranges from 50. The range in volcanic gas composition over time and space is caused by magma degassing, overturn and mixing of partially degassed magma with fresh primary magma beneath Pu`u `O`o. Measurements of the mean rate of magma degassing (from SO2 emissions) and mean lava effusion rate (from geophysical measurements of lava tube flux) suggest that a larger volume (DRE) of magma is degassing than is being erupted, on average. This analysis suggests that magma storage in the Rift Zone might be important during eruptions as

  6. Materials testing for molten carbonate fuel cells

    International Nuclear Information System (INIS)

    Di Mario, F.; Frangini, S.

    1995-01-01

    Unlike conventional generation systems fuel cells use an electrochemical reaction between a fossil fuel and an oxidant to produce electricity through a flame less combustion process. As a result, fuel cells offer interesting technical and operating advantages in terms of conversion efficiencies and environmental benefits due to very low pollutant emissions. Among the different kinds of fuel cells the molten carbonate fuel cells are currently being developed for building compact power generation plants to serve mainly in congested urban areas in virtue of their higher efficiency capabilities at either partial and full loads, good response to power peak loads, fuel flexibility, modularity and, potentially, cost-effectiveness. Starting from an analysis of the most important degradative aspects of the corrosion of the separator plate, the main purpose of this communication is to present the state of the technology in the field of corrosion control of the separator plate in order to extend the useful lifetime of the construction materials to the project goal of 40,000 hours

  7. Molten salt destruction process for mixed wastes

    International Nuclear Information System (INIS)

    Upadhye, R.S.; Wilder, J.G.; Karlsen, C.E.

    1993-04-01

    We are developing an advanced two-stage process for the treatment of mixed wastes, which contain both hazardous and radioactive components. The wastes, together with an oxidant gas, such as air, are injected into a bed of molten salt comprising a mixture of sodium-, potassium-, and lithium-carbonates, with a melting point of about 580 degree C. The organic constituents of the mixed waste are destroyed through the combined effect of pyrolysis and oxidation. Heteroatoms. such as chlorine, in the mixed waste form stable salts, such as sodium chloride, and are retained in the melt. The radioactive actinides in the mixed waste are also retained in the melt because of the combined action of wetting and partial dissolution. The original process, consists of a one-stage unit, operated at 900--1000 degree C. The advanced two-stage process has two stages, one for pyrolysis and one for oxidation. The pyrolysis stage is designed to operate at 700 degree C. The oxidation stage can be operated at a higher temperature, if necessary

  8. Temperatures and isotopic evolution of silicic magmas, Taupo Volcanic Zone and Coromandel, New Zealand

    International Nuclear Information System (INIS)

    Blattner, P.; Rui-Zhong, Hu; Graham, I.J.; Houston-Eleftheriadis, C.

    1996-01-01

    A new set of oxygen and strontium isotope data on rhyolitic lavas and ignimbrites of the Taupo Volcanic Zone (TVZ) and the Coromandel Peninsula provides new limits for petrogenetic models. For oxygen isotopes, the rock matrix is frequently altered, so that values for magma need to be phenocryst based. Within TVZ a trend towards more negative delta 1 8 O values for more recent magmas appears likely (average before about 1 Ma and for Coromandel near 8.0 per thousand; after 1 Ma near 7.5 per thousand). This could indicate the gradual removal of supracrustal contaminants from the zones of magma accumulation and extrusion. Similar trends within Coromandel cannot yet be resolved. A generally positive correlation is found for oxygen and strontium isotopes of magmas. Most magmas have a limited range of isotopic values, which then becomes a useful fingerprint (e.g., the Mamaku, Matahina, and Waiotapu Ignimbrites). A narrow range of eruption temperatures of 880 plus or minus 60degC is derived from quartz-plagioclase fractionations of 0.98 plus or minus 0.25 per thousand delta 1 8 O for 15 magmas. Some delta 1 8 O values of quartz and feldspar phenocrysts are sufficiently low to suggest interaction between surface water and magma. However, large negative oxygen isotope anomalies (such as known from Yellowstone), could be no more than partially concealed by the isotopically less depleted meteoric water of New Zealand, and have not yet been found in New Zealand. (author). 45 refs., 3 tabs., 6 figs

  9. Sr and Nd isotope geochemistry of coexisting alkaline magma series, Cantal, Massif Central, France

    International Nuclear Information System (INIS)

    Downes, H.

    1984-01-01

    Sr and Nd isotope analyses are presented for Tertiary continental alkaline volcanics from Cantal, Massif Central, France. The volcanics belong to two main magma series, silica-saturated and silica-undersaturated (with rare nephelinites). Trace element and isotopic data indicate a common source for the basic parental magmas of both major series; the nephelinites in contrast must have been derived from a mantle source which is isotopically and chemically distinct from that which gave rise to the basalts and basanites. 87 Sr/ 86 Sr initial ratios range from 0.7034 to 0.7056 in the main magma series (excluding rhyolites) and 143 Nd/ 144 Nd ratios vary between 0.512927 and 0.512669; both are correlated with increasing SiO 2 in the lavas. The data can be explained by a model of crustal contamination linked with fractional crystallisation. This indicates that crustal magma chambers are the sites of differentiation since only rarely do evolved magmas not show a crustal isotopic signature and conversely basic magmas have primitive isotopic ratios unless they contain obviuos crustal-derived xenocrysts. Potential contaminants include lower crustal granulites or partial melts of upper crustal units. Equal amounts of contamination are required for both magma series, refuting hypotheses of selective contamination of the silica-saturated series. The isotopic characteristics of the apparently primary nephelinite lavas demonstrates widespread heterogeneity in the mantle beneath Cantal. Some rhyolites, previously thought to be extremely contaminated or to be crustally derived, are shown to have undergone post-emplacement hydrothermal alteration. (orig.)

  10. Compatibility of molten salt and structural materials

    International Nuclear Information System (INIS)

    Kawakami, Masahiro

    1994-01-01

    As the important factors for considering the compatibility of fuel salt and coolant salt with structural materials in molten salt reactors, there are the moisture remaining in molten salt and the fluorine potential in molten salt. In this study, as for the metals which are the main components of corrosion resistant alloys, the corrosion by the moisture remaining in molten salt and the dependence of the corrosion on fluorine potential were examined. As the molten salts, an eutectic molten salt LiF-BeF 2 was mainly used, and LiF-KF was used in combination. As the metallic materials, Cr, Ni and Cu which are the main components of corrosion resistant and heat resistant alloys, Hastelloy and Monel, were used. In the experiment, the metal pieces were immersed in the molten salt, and by sampling the molten salt, the change with time lapse of the concentration of the dissolved metals was examined. Besides, the electrochemical measurement was carried out for Cr, of which the corrosion was remarkable, and the change with time lapse of the dissolved ions was examined. The experimental setup, the experimental method, and the results of the immersion test and the electrochemical test are reported. The experiment on the corrosion of metals depending on fluorine potential is also reported. (K.I.)

  11. Compatibility of molten salt and structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami, Masahiro [Toyohashi Univ. of Technology, Aichi (Japan)

    1994-12-01

    As the important factors for considering the compatibility of fuel salt and coolant salt with structural materials in molten salt reactors, there are the moisture remaining in molten salt and the fluorine potential in molten salt. In this study, as for the metals which are the main components of corrosion resistant alloys, the corrosion by the moisture remaining in molten salt and the dependence of the corrosion on fluorine potential were examined. As the molten salts, an eutectic molten salt LiF-BeF{sub 2} was mainly used, and LiF-KF was used in combination. As the metallic materials, Cr, Ni and Cu which are the main components of corrosion resistant and heat resistant alloys, Hastelloy and Monel, were used. In the experiment, the metal pieces were immersed in the molten salt, and by sampling the molten salt, the change with time lapse of the concentration of the dissolved metals was examined. Besides, the electrochemical measurement was carried out for Cr, of which the corrosion was remarkable, and the change with time lapse of the dissolved ions was examined. The experimental setup, the experimental method, and the results of the immersion test and the electrochemical test are reported. The experiment on the corrosion of metals depending on fluorine potential is also reported. (K.I.).

  12. Fundamentals of molten-salt thermal technology

    International Nuclear Information System (INIS)

    1980-08-01

    This book has been published by the Society of Molten-Salt Thermal Technology to publish a part of the achievement of its members. This book is composed of seven chapters. The chapter 1 is Introduction. The chapter 2 explains the physical properties of molten salts, such as thermal behavior, surface tension, viscosity, electrical conductivity and others. The chapter 3 presents the compatibility with construction materials. Corrosion in molten salts, the electrochemical behavior of fluoride ions on carbon electrodes in fluoride melts, the behaviors of hastelloy N and metals in melts are items of this chapter. The equipments and instruments for molten salts are described in chapter 4. The heat transfer in molten salts is discussed in chapter 5. The chapter 6 explains the application of molten salt technology. The molten salt technology can be applied not only to thermal engineering and energy engineering but also to chemical and nuclear engineerings, and the technical fundamentals, current development status, technical problems and the perspective for the future are outlined. The chapter 7 is the summary of this book. The commercialization of molten salt power reactors is discussed at the end of this book. (Kato, T.)

  13. Metal Production by Molten Salt Electrolysis

    DEFF Research Database (Denmark)

    Grjotheim, K.; Kvande, H.; Qingfeng, Li

    Chemistry and electrochemistry of molten salts are reviewed. Technological aspects of electrolytic production of aluminium, magnesium, and other metals are comprehensively surveyed.......Chemistry and electrochemistry of molten salts are reviewed. Technological aspects of electrolytic production of aluminium, magnesium, and other metals are comprehensively surveyed....

  14. Molten salt processes in special materials preparation

    International Nuclear Information System (INIS)

    Krishnamurthy, N.; Suri, A.K.

    2013-01-01

    As a class, molten salts are the largest collection of non aqueous inorganic solvents. On account of their stability at high temperature and compatibility to a number of process requirements, molten salts are considered indispensable to realize many of the numerous benefits of high temperature technology. They play a crucial role and form the basis for numerous elegant processes for the preparation of metals and materials. Molten salt are considered versatile heat transfer media and have led to the evolution of many interesting reactor concepts in fission and possibly in fusion. They also have been the basis of thinking for few novel processes for power generation. While focusing principally on the actual utilization of molten salts for a variety of materials preparation efforts in BARC, this lecture also covers a few of the other areas of technological applications together with the scientific basis for considering the molten salts in such situations. (author)

  15. Improvement to molten salt reactors

    International Nuclear Information System (INIS)

    Bienvenu, Claude.

    1975-01-01

    The invention proposes a molten salt nuclear reactor whose core includes a mass of at least one fissile element salt to which can be added other salts to lower the melting temperature of the mass. This mass also contains a substance with a low neutron capture section that does not give rise to a chemical reaction or to an azeotropic mixture with these salts and having an atmospheric boiling point under that of the mass in operation. Means are provided for collecting this substance in the vapour state and returning it as a liquid to the mass. The kind of substance chosen will depend on that of the molten salts (fissile element salts and, where required, salts to lower the melting temperature). In actual practice, the substance chosen will have an atmospheric pressure boiling point of between 600 and 1300 0 C and a melting point sufficiently below 600 0 C to prevent solidification and clogging in the return line of the substance from the exchanger. Among the materials which can be considered for use, mention is made of magnesium, rubidium, cesium and potassium but metal cesium is not employed in the case of many fissile salts, such as fluorides, which it would reduced to the planned working temperatures [fr

  16. Eruptive dynamics during magma decompression: a laboratory approach

    Science.gov (United States)

    Spina, L.; Cimarelli, C.; Scheu, B.; Wadsworth, F.; Dingwell, D. B.

    2013-12-01

    the expanding height of the silicone oil column with time after the decompression, due to the exsolution of the volatile argon and subsequent bubble growth. Contrastingly, autoclave-wall resolved shear strain of bubbles promotes rapid coalescence until a critical point when permeable outgassing is more efficient than continuing exsolution and bubble growth. At this point the column destabilizes and partially collapses. Collapse progresses until the top of the column is again impermeable and outgassing-driven column expansion resumes. This process repeats in cycles of growth, deformation, destabilization and densification until the melt is at equilibrium saturation with argon and the column collapses completely. We propose that direct observation of the timescales of growth and collapse of a decompressing, shearing column has important implications for decompression-driven rapid conduit ascent of low-viscosity, low-crystallinity magmas. Therefore, even at high exsolution rates, permeable outgassing can transiently retard magma ascent.

  17. Crustal Thickness Beneath Libya and the Origin of Partial Melt Beneath AS Sawda Volcanic Province From Receiver Function Constraints

    Science.gov (United States)

    Lemnifi, Awad A.; Elshaafi, Abdelsalam; Browning, John; Aouad, Nassib S.; El Ebaidi, Saad K.; Liu, Kelly K.; Gudmundsson, Agust

    2017-12-01

    This study investigates crustal thickness and properties within the Libyan region. Results obtained from 15 seismic stations belonging to the Libyan Center for Remote Sensing and Space Science are reported, in addition to 3 seismic stations publically available, using receiver functions. The results show crustal thicknesses ranging from 24 km to 36 km (with uncertainties ranging between ±0.10 km and ±0.90 km). More specifically, crustal thickness ranges from 32 km to 36 km in the southern portion of the Libyan territory then becomes thinner, between 24 km and 30 km, in the coastal areas of Libya and thinnest, between 24 km and 28 km, in the Sirt Basin. The observed high Vp/Vs value of 1.91 at one station located at the AS Sawda Volcanic Province in central Libya indicates the presence of either partial melt or an abnormally warm area. This finding suggests that magma reservoirs beneath the Libyan territory may still be partially molten and active, thereby posing significant earthquake and volcanic risks. The hypothesis of an active magma source is further demonstrated though the presence of asthenospheric upwelling and extension of the Sirt Basin. This study provides a new calculation of unconsolidated sediment layers by using the arrival time of the P to S converted phases. The results show sediments thicknesses of 0.4 km to 3.7 km, with the Vp/Vs values ranging from 2.2 to 4.8. The variations in crustal thickness throughout the region are correlated with surface elevation and Bouguer gravity anomalies, which suggest that they are isostatically compensated.

  18. The timing of compositionally-zoned magma reservoirs and mafic 'priming' weeks before the 1912 Novarupta-Katmai rhyolite eruption

    Science.gov (United States)

    Singer, Brad S.; Costa, Fidel; Herrin, Jason S.; Hildreth, Wes; Fierstein, Judith

    2016-01-01

    The June 6, 1912 eruption of more than 13 km3 of dense rock equivalent (DRE) magma at Novarupta vent, Alaska was the largest of the 20th century. It ejected >7 km3 of rhyolite, ~1.3 km3 of andesite and ~4.6 km3 of dacite. Early ideas about the origin of pyroclastic flows and magmatic differentiation (e.g., compositional zonation of reservoirs) were shaped by this eruption. Despite being well studied, the timing of events that led to the chemically and mineralogically zoned magma reservoir remain poorly known. Here we provide new insights using the textures and chemical compositions of plagioclase and orthopyroxene crystals and by reevaluating previous U-Th isotope data. Compositional zoning of the magma reservoir likely developed a few thousand years before the eruption by several additions of mafic magma below an extant silicic reservoir. Melt compositions calculated from Sr contents in plagioclase fill the compositional gap between 68 and 76% SiO2 in whole pumice clasts, consistent with uninterrupted crystal growth from a continuum of liquids. Thus, our findings support a general model in which large volumes of crystal-poor rhyolite are related to intermediate magmas through gradual separation of melt from crystal-rich mush. The rhyolite is incubated by, but not mixed with, episodic recharge pulses of mafic magma that interact thermochemically with the mush and intermediate magmas. Hot, Mg-, Ca-, and Al-rich mafic magma intruded into, and mixed with, deeper parts of the reservoir (andesite and dacite) multiple times. Modeling the relaxation of the Fe-Mg concentrations in orthopyroxene and Mg in plagioclase rims indicates that the final recharge event occurred just weeks prior to the eruption. Rapid addition of mass, volatiles, and heat from the recharge magma, perhaps aided by partial melting of cumulate mush below the andesite and dacite, pressurized the reservoir and likely propelled a ~10 km lateral dike that allowed the overlying rhyolite to reach the surface.

  19. Production of Oxygen from Lunar Regolith by Molten Oxide Electrolysis

    Science.gov (United States)

    Curreri, Peter A.

    2009-01-01

    This paper describes the use of the molten oxide electrolysis (MOE) process for the extraction of oxygen for life support and propellant, and silicon and metallic elements for use in fabrication on the Moon. The Moon is rich in mineral resources, but it is almost devoid of chemical reducing agents, therefore, molten oxide electrolysis is ideal for extraction, since the electron is the only practical reducing agent. MOE has several advantages over other extraction methods. First, electrolytic processing offers uncommon versatility in its insensitivity to feedstock composition. Secondly, oxide melts boast the twin key attributes of highest solubilizing capacity for regolith and lowest volatility of any candidate electrolytes. The former is critical in ensuring high productivity since cell current is limited by reactant solubility, while the latter simplifies cell design by obviating the need for a gas-tight reactor to contain evaporation losses as would be the case with a gas or liquid phase fluoride reagent operating at such high temperatures. Alternatively, MOE requires no import of consumable reagents (e.g. fluorine and carbon) as other processes do, and does not rely on interfacing multiple processes to obtain refined products. Electrolytic processing has the advantage of selectivity of reaction in the presence of a multi-component feed. Products from lunar regolith can be extracted in sequence according to the stabilities of their oxides as expressed by the values of the free energy of oxide formation (e.g. chromium, manganese, Fe, Si, Ti, Al, magnesium, and calcium). Previous work has demonstrated the viability of producing Fe and oxygen from oxide mixtures similar in composition to lunar regolith by molten oxide electrolysis (electrowinning), also called magma electrolysis having shown electrolytic extraction of Si from regolith simulant. This paper describes recent advances in demonstrating the MOE process by a joint project with participation by NASA KSC and

  20. Radiographic visualization of magma dynamics in an erupting volcano.

    Science.gov (United States)

    Tanaka, Hiroyuki K M; Kusagaya, Taro; Shinohara, Hiroshi

    2014-03-10

    Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography) with dynamic radiographic imaging. Time sequential radiographic images show that the top of the magma column ascends right beneath the crater floor through which the eruption column was observed. In addition to the visualization of this magma inflation, we report a sequence of images that show magma descending. We further propose that the monitoring of temporal variations in the gas volume fraction of magma as well as its position in a conduit can be used to support existing eruption prediction procedures.

  1. Redox Evolution in Magma Oceans Due to Ferric/Ferrous Iron Partitioning

    Science.gov (United States)

    Schaefer, L.; Elkins-Tanton, L. T.; Pahlevan, K.

    2017-12-01

    A long-standing puzzle in the evolution of the Earth is that while the present day upper mantle has an oxygen fugacity close to the QFM buffer, core formation during accretion would have occurred at much lower oxygen fugacities close to IW. We present a new model based on experimental evidence that normal solidification and differentiation processes in the terrestrial magma ocean may explain both core formation and the current oxygen fugacity of the mantle without resorting to a change in source material or process. A commonly made assumption is that ferric iron (Fe3+) is negligible at such low oxygen fugacities [1]. However, recent work on Fe3+/Fe2+ ratios in molten silicates [2-4] suggests that the Fe3+ content should increase at high pressure for a given oxygen fugacity. While disproportionation was not observed in these experiments, it may nonetheless be occurring in the melt at high pressure [5]. Therefore, there may be non-negligible amounts of Fe3+ formed through metal-silicate equilibration at high pressures within the magma ocean. Homogenization of the mantle and further partitioning of Fe2+/Fe3+ as the magma ocean crystallizes may explain the oxygen fugacity of the Earth's mantle without requiring additional oxidation mechanisms. We present here models using different parameterizations for the Fe2+/Fe3+ thermodynamic relationships in silicate melts to constrain the evolution of the redox state of the magma ocean as it crystallizes. The model begins with metal-silicate partitioning at high pressure to form the core and set the initial Fe3+ abundance. Combined with previous work on oxygen absorption by magma oceans due to escape of H from H2O [6], we show that the upper layers of solidifying magma oceans should be more oxidized than the lower mantle. This model also suggests that large terrestrial planets should have more oxidized mantles than small planets. From a redox perspective, no change in the composition of the Earth's accreting material needs to be

  2. Rapid Crystallization of the Bishop Magma

    Science.gov (United States)

    Gualda, G. A.; Anderson, A. T.; Sutton, S. R.

    2007-12-01

    Substantial effort has been made to understand the longevity of rhyolitic magmas, and particular attention has been paid to the systems in the Long Valley area (California). Recent geochronological data suggest discrete magma bodies that existed for hundreds of thousands of years. Zircon crystallization ages for the Bishop Tuff span 100-200 ka, and were interpreted to reflect slow crystallization of a liquid-rich magma. Here we use the diffusional relaxation of Ti zoning in quartz to investigate the longevity of the Bishop magma. We have used such an approach to show the short timescales of crystallization of Ti-rich rims on quartz from early- erupted Bishop Tuff. We have now recognized Ti-rich cores in quartz that can be used to derive the timescales of their crystallization. We studied four samples of the early-erupted Bishop. Hand-picked crystals were mounted on glass slides and polished. Cathodoluminescence (CL) images were obtained using the electron microprobe at the University of Chicago. Ti zoning was documented using the GeoSoilEnviroCARS x-ray microprobe at the Advanced Photon Source (Argonne National Lab). Quartz crystals in all 4 samples include up to 3 Ti-bearing zones: a central core (50-100 μm in diameter, ca. 50 ppm Ti), a volumetrically predominant interior (~40 ppm Ti), and in some crystals a 50-100 μm thick rim (50 ppm Ti). Maximum estimates of core residence times were calculated using a 1D diffusion model, as the time needed to smooth an infinitely steep profile to fit the observed profile. Surprisingly, even for the largest crystals studied - ca. 2 mm in diameter - core residence times are less than 1 ka. Calculated growth rates imply that even cm-sized crystals crystallized in less than 10 ka. Crystal size distribution data show that crystals larger than 3 mm are exceedingly rare, such that the important inference is that the bulk of the crystallization of the early-erupted Bishop magma occurred in only a few thousand years. This timescale

  3. Sampling device for radioactive molten salt

    International Nuclear Information System (INIS)

    Shindo, Masato

    1998-01-01

    The present invention provides a device for accurately sampling molten salts to which various kinds of metals in a molten salt storage tank are mixed for analyzing them during a spent fuel dry type reprocessing. Namely, the device comprises a sampling tube having an opened lower end to be inserted into the radioactive molten salts stored in a tank and keeps reduced pressure from the upper end, and a pressure reducing pipeline having one end connected to the sampling tube and other end connected to an evacuating pump. In this device, the top end of the sampling tube is inserted to a position for sampling the radioactive molten salts (molten salts). The pressure inside the evacuating pipeline connected to the upper portion of the sampling tube is reduced for a while. In this case, the inside of the pressure reducing pipeline is previously evacuated by the evacuating pump so as to keep a predetermined pressure. Since the pressure in the sampling tube is lowered, molten salts are inserted into the sampling tube, the sampling tube is withdrawn, and the molten salts flown in the sampling tube are analyzed. (I.S.)

  4. Inter ionic pair potentials for molten copper halides CuX (X=Br, I)

    International Nuclear Information System (INIS)

    Canan, C.

    2004-01-01

    In this work, the inter-ionic pair interactions of molten CuBr and Cu I are described with three different form of the rigid ion model potentials (RIM) using i) the functional form originally proposed by Vasishta and Rahman ii) the form used Madden and coworkers which is include the polarization contributions iii) the form parameterizied by Tatlipinar et al. The capability of these potentials have been discussed with each other by calculating the static liquid structure. We present the results of the partial pair distributions for molten CuBr at 810K and for molten Cul at 940K comparing with experimental data. The structural calculations are performed by solving the numerically the hypemetted chain approximate theory of liquids

  5. Magma interaction in the root of an arc batholith

    Science.gov (United States)

    Chapman, T.; Robbins, V.; Clarke, G. L.; Daczko, N. R.; Piazolo, S.

    2016-12-01

    Fiordland, New Zealand, preserves extensive Cretaceous arc plutons, emplaced into parts of the Delamerian/Ross Orogen. Dioritic to gabbroic material emplaced at mid to lower crustal levels are exposed in the Malaspina Pluton (c. 1.2 GPa) and the Breaksea Orthogneiss (c. 1.8 GPa). Distinct magmatic pulses can be mapped in both of these plutons consistent with cycles of melt advection. Relationships are consistent with predictions from lower crustal processing zones (MASH and hot zones) considered important in the formation of Cordilleran margins. Metamorphic garnet growth is enhanced along magmatic contacts, such as where hornblende gabbronorite is cut by garnet-clinopyroxene-bearing diorite. Such features are consistent with cycles of incremental emplacement, younger magma having induced localised garnet granulite metamorphism in wall rock of older material. Temperature estimates and microstructures preserved in garnet granulite are consistent with sub-solidus, water-poor conditions in both the Malaspina and Breaksea Orthogneiss. The extent and conditions of the metamorphism implies conditions and duration was incapable of partially melting older wall rock material. The nature of interactions in intermediate to basic compositions are assessed in terms of magma genesis in the Cretaceous batholith. Most of the upper crustal felsic I-type magmatism along the margin being controlled by high-pressure garnet-clinopyroxene fractionation.

  6. Inertia-confining thermonuclear molten salt reactors

    International Nuclear Information System (INIS)

    Furukawa, Kazuo; Yamanaka, Chiyoe; Nakai, Sadao; Imon, Shunji; Nakajima, Hidenori; Nakamura, Norio; Kato, Yoshio.

    1984-01-01

    Purpose: To increase the heat generating efficiency while improving the reactor safety and thereby maintaining the energy balance throughout the reactor. Constitution: In an inertia-confining type D-T thermonuclear reactor, the blanket is made of lithium-containing fluoride molten salts (LiF.BeF 2 , LiF.NaF.KF, LiF.KF, etc) which are cascaded downwardly in a large thickness (50 - 100 cm) along the inner wall of the thermonuclear reaction vessel, and neutrons generated by explosive compression are absorbed to lithium in the molten salts to produce tritium, Heat transportation is carried out by the molten salts. (Ikeda, J.)

  7. Magma wagging and whirling in volcanic conduits

    Science.gov (United States)

    Liao, Yang; Bercovici, David; Jellinek, Mark

    2018-02-01

    Seismic tremor characterized by 0.5-7 Hz ground oscillations commonly occur before and during eruptions at silicic volcanoes with widely ranging vent geometries and edifice structures. The ubiquitous characteristics of this tremor imply that its causes are potentially common to silicic volcanoes. Here we revisit and extend to three dimensions the magma-wagging model for tremor (Jellinek and Bercovici, 2011; Bercovici et al., 2013), wherein a stiff magma column rising in a vertical conduit oscillates against a surrounding foamy annulus of bubbly magma, giving rise to tremor. While prior studies were restricted to two-dimensional lateral oscillations, here we explore three-dimensional motion and additional modes of oscillations. In the absence of viscous damping, the magma column undergoes 'whirling' motion: the center of each horizontal section of the column traces an elliptical trajectory. In the presence of viscous effect we identify new 'coiling' and 'uncoiling' column bending shapes with relatively higher and comparable rates of dissipation to the original two-dimensional magma wagging model. We also calculate the seismic P-wave response of the crustal material around the volcanic conduit to the new whirling motions and propose seismic diagnostics for different wagging patterns using the time-lag between seismic stations. We test our model by analyzing pre-eruptive seismic data from the 2009 eruption of Redoubt Volcano. In addition to suggesting that the occurrence of elliptical whirling motion more than 1 week before the eruption, our analysis of seismic time-lags also implies that the 2009 eruption was accompanied by qualitative changes in the magma wagging behavior including fluctuations in eccentricity and a reversal in the direction of elliptical whirling motion when the eruption was immediately impending.

  8. Structure and thermodynamics of molten salts

    International Nuclear Information System (INIS)

    Papatheodorou, G.N.

    1983-01-01

    This chapter investigates single-component molten salts and multicomponent salt mixtures. Molten salts provide an important testing ground for theories of liquids, solutions, and plasmas. Topics considered include molten salts as liquids (the pair potential, the radial distribution function, methods of characterization), single salts (structure, thermodynamic correlations), and salt mixtures (the thermodynamics of mixing; spectroscopy and structure). Neutron and X-ray scattering techniques are used to determine the structure of molten metal halide salts. The corresponding-states theory is used to obtain thermodynamic correlations on single salts. Structural information on salt mixtures is obtained by using vibrational (Raman) and electronic absorption spectroscopy. Charge-symmetrical systems and charge-unsymmetrical systems are used to examine the thermodynamics of salt mixtures

  9. Waste treatment using molten salt oxidation

    International Nuclear Information System (INIS)

    Navratil, J.D.; Stewart, A.E.

    1996-01-01

    MSO technology can be characterized as a submerged oxidation process; the basic concept is to introduce air and wastes into a bed of molten salt, oxidize the organic wastes in the molten salt, use the heat of oxidation to keep the salt molten and remove the salt for disposal or processing and recycling. The molten salt (usually sodium carbonate at 900-1000 C) provides four waste management functions: providing a heat transfer medium, catalyzing the oxidation reaction, preventing the formation of acid gases by forming stable salts, and efficiently capturing ash particles and radioactive materials by the combined effects of wetting, encapsulation and dissolution. The MSO process requires no wet scrubbing system for off-gas treatment. The process has been developed through bench-scale and pilot-scale testing, with successful destruction demonstration of a wide variety of hazardous and mixed (radioactive and hazardous wastes). (author). 24 refs, 2 tabs, 2 figs

  10. Artificial magma and applications of the blasting technique

    Energy Technology Data Exchange (ETDEWEB)

    Ichioka, K [Chugoku Kaki KK, Japan

    1974-01-01

    Artifical magma is discussed. Solid magma is a high temperature source and fluid magma is also a heat carrier. Iron ores are examples of solid magma, silica-borate is an example of a hydrophobic heat carrier magma assuming a liquid phase at 600/sup 0/C, and S, Ag, Pb, etc. are also examples of heat carrier magma. In addition to these examples, basic salts such as NaNO/sub 3/, KNO/sub 3/, NaCl, CaCl, KCl, BaCl, and Na/sub 4/B/sub 4/O/sub 7/ can be used as artifical magma. These are artifical magmas or heat mediums capable of capturing geothermal heat when circulated inside volcanoes. The blasting technique's applications in geothermal wells are also discussed. The technique can be used to expand a well's diameter, repair the well bottom, regenerate old wells, clean wells, or cut steel pipe. Two figures and one table are provided.

  11. Molten salts processes and generic simulation

    International Nuclear Information System (INIS)

    Ogawa, Toru; Minato, Kazuo

    2001-01-01

    Development of dry separation process (pyrochemical process) using molten salts for the application of spent-nuclear fuel reprocessing requires a rather complete fundamental database as well as process simulation technique with wide applicability. The present report concerns recent progress and problems in this field taking behaviors of co-electrodeposition of UO 2 and PuO 2 in molten salts as an example, and using analytical simulation of local equilibrium combined with generic diffusion. (S. Ohno)

  12. Molten salts processes and generic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Toru; Minato, Kazuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-12-01

    Development of dry separation process (pyrochemical process) using molten salts for the application of spent-nuclear fuel reprocessing requires a rather complete fundamental database as well as process simulation technique with wide applicability. The present report concerns recent progress and problems in this field taking behaviors of co-electrodeposition of UO{sub 2} and PuO{sub 2} in molten salts as an example, and using analytical simulation of local equilibrium combined with generic diffusion. (S. Ohno)

  13. Controlling the discharge of molten material

    International Nuclear Information System (INIS)

    Geel, J. van; Dobbels, F.; Theunissen, W.

    1980-01-01

    A method and device are described for controlling the discharge of molten material from a melter or an intermediate vessel, in which a primary outflow is fed to an overflow system, the working level of which is regulated by means of pneumatic pressure on a communicating chamber pertaining to the overflow system. Molten material may be led into a primary overflow by means of a pneumatic lift. The material melted may be a glass used for disposing of radioactive liquid wastes. (author)

  14. Electrochemical ion separation in molten salts

    Science.gov (United States)

    Spoerke, Erik David; Ihlefeld, Jon; Waldrip, Karen; Wheeler, Jill S.; Brown-Shaklee, Harlan James; Small, Leo J.; Wheeler, David R.

    2017-12-19

    A purification method that uses ion-selective ceramics to electrochemically filter waste products from a molten salt. The electrochemical method uses ion-conducting ceramics that are selective for the molten salt cations desired in the final purified melt, and selective against any contaminant ions. The method can be integrated into a slightly modified version of the electrochemical framework currently used in pyroprocessing of nuclear wastes.

  15. Magma evolution in the Pliocene Pleistocene succession of Kos, South Aegean arc (Greece)

    Science.gov (United States)

    Pe-Piper, Georgia; Moulton, Ben

    2008-11-01

    This study investigates the petrogenesis of Pliocene-Quaternary andesites, dacites and rhyolites of the island of Kos. These volcanic rocks differ from other volcanic centres in the South Aegean arc in the narrow range of Pliocene volcanic products, the abundance of high-silica rhyolite, the lower ɛNd for a given Sr isotope composition, and greater depth to the subducting slab. Pliocene and early Pleistocene dacite stocks and rhyolite domes are succeeded by younger tuffs, notably the 0.16 Ma Kos Plateau Tuff derived from a super-eruption of an andesite stratocone now subsided beneath the sea south of Kos. Volcanic products in tuffs have been sampled from lithic clasts. Andesite, dacite and rhyolite all have ɛNd ˜+ 1.5 to -1.5 and 86Sr/ 87Sr ˜ 0.7042; this unusual composition is argued to be the result of subduction of sediments derived from the River Nile. All rock types show structures indicative of widespread magma mixing, including complexly zoned plagioclase, clinopyroxene and amphibole containing glass inclusions of trachyte and rhyolite compositions. The observed rocks result from fractionation and mixing of three principal magma types: (a) calc-alkaline high-Al basalt that fractionated to andesite at the base of crust; (b) partially melted metabasaltic amphibolite underplated at the base of crust, that fractionated to produce high-SiO 2 rhyolite; and (c) a minor component of trachytic magma from partial melting of enriched subcontinental lithospheric mantle. The complexly zoned phenocrysts with glass inclusions provide specific evidence for mixing of these three components. Specifically, it was the emplacement of the andesite into a voluminous rhyolite magma in a mid-crustal magma chamber that led to the explosive Kos Plateau Tuff super-eruption.

  16. Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks

    Science.gov (United States)

    Coombs, Michelle L.; Bacon, Charles R.

    2012-01-01

    Alaska is one of the most vigorously volcanic regions on the planet, and Alaska’s national parks are home to many of the state’s most active volcanoes. These pose both local and more distant hazards in the form of lava and pyroclastic flows, lahars (mudflows), ash clouds, and ash fall. Alaska’s volcanoes lie along the arc of the Aleutian-Alaskan subduction zone, caused as the oceanic Pacific plate moves northward and dips below the North American plate. These volcanoes form as water-rich fluid from the down-going Pacific plate is released, lowering the melting temperature of rock in the overlying mantle and enabling it to partially melt. The melted rock (magma) migrates upward, collecting at the base of the approximately 25 mile (40 km) thick crust, occasionally ascending into the shallow crust, and sometimes erupting at the earth’s surface.During volcanic unrest, scientists use geophysical signals to remotely visualize volcanic processes, such as movement of magma in the upper crust. In addition, erupted volcanic rocks, which are quenched samples of magmas, can tell us about subsurface magma characteris-tics, history, and the processes that drive eruptions. The chemical compositions of and the minerals present in the erupted magmas can reveal conditions under which these magmas were stored in crustal “chambers”. Studies of the products of recent eruptions of Novarupta (1912), Aniakchak (1931), Trident (1953-74), and Redoubt (2009) volcanoes reveal the depths and temperatures of magma storage, and tell of complex interactions between magmas of different compositions. One goal of volcanology is to determine the processes that drive or trigger eruptions. Information recorded in the rocks tells us about these processes. Here, we demonstrate how geologists gain these insights through case studies from four recent eruptions of volcanoes in Alaska national parks.

  17. Regulatory, Land Ownership, and Water Availability Factors for a Magma Well: Long Valley Caldera and Coso Hot Springs, California

    Energy Technology Data Exchange (ETDEWEB)

    Blackett, Robert

    1985-09-01

    The U.S. Department of Energy is currently engaged in a program to demonstrate the engineering feasibility of extracting thermal energy from high-level molten magma bodies. The program is being carried out under the direction of Sandia National Laboratories where a number of individual projects support the overall program. The existing program elements include (1) high-temperature materials compatibility testing; (2) studies of properties of melts of various compositions; and (3) the investigation of the economics of a magma energy extraction system. Another element of the program is being conducted with the cooperation of the U.S. Geological Survey, and involves locating and outlining magma bodies at selected sites using various geophysical techniques. The ultimate goal here will be to define the limits of a magma body as a drilling target. During an earlier phase of the program, more than twenty candidate study sites considered were evaluated based upon: (1) the likelihood of the presence of a shallow magma chamber, (2) the accessibility of the site, and (3) physical and institutional constraints associated with each site with respect to performing long-term experiments. From these early phase activities, the number of candidate sites were eventually narrowed to just 2. The sites currently under consideration are Coso Hot Springs and the Long Valley caldera (Figure 1). This report describes certain attributes of these sites in order to help identify potential problems related to: (1) state and federal regulations pertaining to geothermal development; (2) land ownership; and (3) water resource availability. The information sources used in this study were mainly maps, publications, and informative documents gathered from the California Division of Oil and Gas and the U.S. Department of the Interior. Environmental studies completed for the entire Long Valley caldera study area, and for portions of the Coso Hot Springs study area were also used for reference.

  18. Loki Patera: A Magma Sea Story

    Science.gov (United States)

    Veeder, G. J.; Matson, D. L.; Rathbun, A. G.

    2005-01-01

    We consider Loki Patera on Io as the surface expression of a large uniform body of magma. Our model of the Loki magma sea is some 200 km across; larger than a lake but smaller than an ocean. The depth of the magma sea is unknown, but assumed to be deep enough that bottom effects can be ignored. Edge effects at the shore line can be ignored to first order for most of the interior area. In particular, we take the dark material within Loki Patera as a thin solidified lava crust whose hydrostatic shape follows Io's isostatic surface (approx. 1815 km radius of curvature). The dark surface of Loki appears to be very smooth on both regional and local (subresolution) scales. The thermal contrast between the low and high albedo areas within Loki is consistent with the observed global correlation. The composition of the model magma sea is basaltic and saturated with dissolved SO2 at depth. Its average, almost isothermal, temperature is at the liquidus for basalt. Additional information is included in the original extended abstract.

  19. Probing magma reservoirs to improve volcano forecasts

    Science.gov (United States)

    Lowenstern, Jacob B.; Sisson, Thomas W.; Hurwitz, Shaul

    2017-01-01

    When it comes to forecasting eruptions, volcano observatories rely mostly on real-time signals from earthquakes, ground deformation, and gas discharge, combined with probabilistic assessments based on past behavior [Sparks and Cashman, 2017]. There is comparatively less reliance on geophysical and petrological understanding of subsurface magma reservoirs.

  20. Iron Redox Systematics of Martian Magmas

    Science.gov (United States)

    Righter, K.; Danielson, L.; Martin, A.; Pando, K.; Sutton, S.; Newville, M.

    2011-01-01

    Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite [1]. Morris et al. [1] propose that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks [2,3]. Magnetite stability in terrestrial magmas is well understood, as are the stability of FeO and Fe2O3 in terrestrial magmas [4,5]. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas we have undertaken an experimental study with two emphases. First we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition. Second, we determine the FeO and Fe2O3 contents of the same shergottite bulk composition at 1 bar and variable fO2 at 1250 C, and at variable pressure. These two goals will help define not only magnetite stability, but pyroxene-melt equilibria that are also dependent upon fO2.

  1. Unusual Iron Redox Systematics of Martian Magmas

    Science.gov (United States)

    Danielson, L.; Righter, K.; Pando, K.; Morris, R. V.; Graff, T.; Agresti, D.; Martin, A.; Sutton, S.; Newville, M.; Lanzirotti, A.

    2012-01-01

    Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite. Morris et al. proposed that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks. Magnetite stability in terrestrial magmas is well understood, as are the stabilities of FeO and Fe2O3 in terrestrial magmas. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas, we have undertaken an experimental study with two emphases. First, we determine the FeO and Fe2O3 contents of super- and sub-liquidus glasses from a shergottite bulk composition at 1 bar to 4 GPa, and variable fO2. Second, we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition.

  2. Magma-poor vs. magma-rich continental rifting and breakup in the Labrador Sea

    Science.gov (United States)

    Gouiza, M.; Paton, D.

    2017-12-01

    Magma-poor and magma-rich rifted margins show distinct structural and stratigraphic geometries during the rift to breakup period. In magma-poor margins, crustal stretching is accommodated mainly by brittle faulting and the formation of wide rift basins shaped by numerous graben and half-graben structures. Continental breakup and oceanic crust accretion are often preceded by a localised phase of (hyper-) extension where the upper mantle is embrittled, serpentinized, and exhumed to the surface. In magma-rich margins, the rift basin is narrow and extension is accompanied by a large magmatic supply. Continental breakup and oceanic crust accretion is preceded by the emplacement of a thick volcanic crust juxtaposing and underplating a moderately thinned continental crust. Both magma-poor and magma-rich rifting occur in response to lithospheric extension but the driving forces and processes are believed to be different. In the former extension is assumed to be driven by plate boundary forces, while in the latter extension is supposed to be controlled by sublithospheric mantle dynamics. However, this view fails in explaining observations from many Atlantic conjugate margins where magma-poor and magma-rich segments alternate in a relatively abrupt fashion. This is the case of the Labrador margin where the northern segment shows major magmatic supply during most of the syn-rift phase which culminate in the emplacement of a thick volcanic crust in the transitional domain along with high density bodies underplating the thinned continental crust; while the southern segment is characterized mainly by brittle extension, mantle seprentinization and exhumation prior to continental breakup. In this work, we use seismic and potential field data to describe the crustal and structural architectures of the Labrador margin, and investigate the tectonic and mechanical processes of rifting that may have controlled the magmatic supply in the different segments of the margin.

  3. Apparatus for making molten silicon

    Science.gov (United States)

    Levin, Harry (Inventor)

    1988-01-01

    A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

  4. The mechanics of shallow magma reservoir outgassing

    Science.gov (United States)

    Parmigiani, A.; Degruyter, W.; Leclaire, S.; Huber, C.; Bachmann, O.

    2017-08-01

    Magma degassing fundamentally controls the Earth's volatile cycles. The large amount of gas expelled into the atmosphere during volcanic eruptions (i.e., volcanic outgassing) is the most obvious display of magmatic volatile release. However, owing to the large intrusive:extrusive ratio, and considering the paucity of volatiles left in intrusive rocks after final solidification, volcanic outgassing likely constitutes only a small fraction of the overall mass of magmatic volatiles released to the Earth's surface. Therefore, as most magmas stall on their way to the surface, outgassing of uneruptible, crystal-rich magma storage regions will play a dominant role in closing the balance of volatile element cycling between the mantle and the surface. We use a numerical approach to study the migration of a magmatic volatile phase (MVP) in crystal-rich magma bodies ("mush zones") at the pore scale. Our results suggest that buoyancy-driven outgassing is efficient over crystal volume fractions between 0.4 and 0.7 (for mm-sized crystals). We parameterize our pore-scale results for MVP migration in a thermomechanical magma reservoir model to study outgassing under dynamical conditions where cooling controls the evolution of the proportion of crystal, gas, and melt phases and to investigate the role of the reservoir size and the temperature-dependent viscoelastic response of the crust on outgassing efficiency. We find that buoyancy-driven outgassing allows for a maximum of 40-50% volatiles to leave the reservoir over the 0.4-0.7 crystal volume fractions, implying that a significant amount of outgassing must occur at high crystal content (>0.7) through veining and/or capillary fracturing.

  5. Io: Loki Patera as a Magma Sea

    Science.gov (United States)

    Matson, Dennis L.; Davies, Ashley Gerard; Veeder, Glenn J.; Rathbun, Julie A.; Johnson, Torrence V.; Castillo, Julie C.

    2006-01-01

    We develop a physical model for Loki Patera as a magma sea. We calculate the total volume of magma moving through the Loki Patera volcanic system every resurfacing cycle (approx.540 days) and the resulting variation in thermal emission. The rate of magma solidification at times reaches 3 x 10(exp 6) kg per second, with a total solidified volume averaging 100 cu km per year. A simulation of gas physical chemistry evolution yields the crust porosity profile and the timescale when it will become dense enough to founder in a manner consistent with observations. The Loki Patera surface temperature distribution shows that different areas are at different life cycle stages. On a regional scale, however, there can be coordinated activity, indicated by the wave of thermal change which progresses from Loki Patera's SW quadrant toward the NE at a rate of approx.1 km per day. Using the observed surface temperature distribution, we test several mechanisms for resurfacing Loki Patera, finding that resurfacing with lava flows is not realistic. Only the crustal foundering process is consistent with observations. These tests also discovered that sinking crust has a 'heat deficit' which promotes the solidification of additional magma onto the sinking plate ("bulking up"). In the limiting case, the mass of sinking material can increase to a mass of approx.3 times that of the foundering plate. With all this solid matter sinking, there is a compensating upward motion in the liquid magma. This can be in excess of 2 m per year. In this manner, solid-liquid convection is occurring in the sea.

  6. Timescale of Petrogenetic Processes Recorded in the Mount Perkins Magma System, Northern Colorado River Extension Corridor, Arizona

    Science.gov (United States)

    Danielson, Lisa R.; Metcalf, Rodney V.; Miller, Calvin F.; Rhodes Gregory T.; Wooden, J. L.

    2013-01-01

    The Miocene Mt. Perkins Pluton is a small composite intrusive body emplaced in the shallow crust as four separate phases during the earliest stages of crustal extension. Phase 1 (oldest) consists of isotropic hornblende gabbro and a layered cumulate sequence. Phase 2 consists of quartz monzonite to quartz monzodiorite hosting mafic microgranitoid enclaves. Phase 3 is composed of quartz monzonite and is subdivided into mafic enclave-rich zones and enclave-free zones. Phase 4 consists of aphanitic dikes of mafic, intermediate and felsic compositions hosting mafic enclaves. Phases 2-4 enclaves record significant isotopic disequilibrium with surrounding granitoid host rocks, but collectively enclaves and host rocks form a cogenetic suite exhibiting systematic variations in Nd-Sr-Pb isotopes that correlate with major and trace elements. Phases 2-4 record multiple episodes of magma mingling among cogenetic hybrid magmas that formed via magma mixing and fractional crystallization at a deeper crustal. The mafic end-member was alkali basalt similar to nearby 6-4 Ma basalt with enriched OIB-like trace elements and Nd-Sr-Pb isotopes. The felsic end-member was a subalkaline crustal-derived magma. Phase 1 isotropic gabbro exhibits elemental and isotopic compositional variations at relatively constant SiO2, suggesting generation of isotropic gabbro by an open-system process involving two mafic end-members. One end-member is similar in composition to the OIB-like mafic end-member for phases 2-4; the second is similar to nearby 11-8 Ma tholeiite basalt exhibiting low epsilon (sub Nd), and depleted incompatible trace elements. Phase 1 cumulates record in situ fractional crystallization of an OIB-like mafic magma with isotopic evidence of crustal contamination by partial melts generated in adjacent Proterozoic gneiss. The Mt Perkins pluton records a complex history in a lithospheric scale magma system involving two distinct mantle-derived mafic magmas and felsic magma sourced in the

  7. Mantle to surface degassing of alkalic magmas at Erebus volcano, Antarctica

    Science.gov (United States)

    Oppenheimer, C.; Moretti, R.; Kyle, P.R.; Eschenbacher, A.; Lowenstern, J. B.; Hervig, R.L.; Dunbar, N.W.

    2011-01-01

    Continental intraplate volcanoes, such as Erebus volcano, Antarctica, are associated with extensional tectonics, mantle upwelling and high heat flow. Typically, erupted magmas are alkaline and rich in volatiles (especially CO2), inherited from low degrees of partial melting of mantle sources. We examine the degassing of the magmatic system at Erebus volcano using melt inclusion data and high temporal resolution open-path Fourier transform infrared (FTIR) spectroscopic measurements of gas emissions from the active lava lake. Remarkably different gas signatures are associated with passive and explosive gas emissions, representative of volatile contents and redox conditions that reveal contrasting shallow and deep degassing sources. We show that this unexpected degassing signature provides a unique probe for magma differentiation and transfer of CO2-rich oxidised fluids from the mantle to the surface, and evaluate how these processes operate in time and space. Extensive crystallisation driven by CO2 fluxing is responsible for isobaric fractionation of parental basanite magmas close to their source depth. Magma deeper than 4kbar equilibrates under vapour-buffered conditions. At shallower depths, CO2-rich fluids accumulate and are then released either via convection-driven, open-system gas loss or as closed-system slugs that ascend and result in Strombolian eruptions in the lava lake. The open-system gases have a reduced state (below the QFM buffer) whereas the closed-system gases preserve their deep oxidised signatures (close to the NNO buffer). ?? 2011 Elsevier B.V.

  8. An attempt to model the timing of magma formation by means of radioactive disequilibria

    International Nuclear Information System (INIS)

    Cortini, M.

    1985-01-01

    In order to quantitatively determine the timing of magma formation, the Th series radioactive disequilibria for the Etna and Stromboli volcanoes have been re-examined in the light of new isotopic evidence that shows that magma formation is a chemically open-system process. This aim was but partially reached. It is shown that single-stage models of magma formation are not consistent with the experimental data. Short-life disequilibria require that magma formation undergoes: (1) a Th and Ra enrichment stage (a few years long); (2) a closed-system stage (a few tens to some hundreds years long); (3) a second Th and Ra enrichment stage (a few years long), different from the former in terms of Ra/Th ratio. The whole process can be described by a group of equations, derived from open-system non-equilibrium thermodynamics, which were integrated with numerical methods. However, too many unknowns are involved to allow a one-to-one solution based on the available data. (orig.)

  9. A method of measuring a molten metal liquid pool volume

    Science.gov (United States)

    Garcia, G.V.; Carlson, N.M., Donaldson, A.D.

    1990-12-12

    A method of measuring a molten metal liquid pool volume and in particular molten titanium liquid pools, including the steps of (a) generating an ultrasonic wave at the surface of the molten metal liquid pool, (b) shining a light on the surface of a molten metal liquid pool, (c) detecting a change in the frequency of light, (d) detecting an ultrasonic wave echo at the surface of the molten metal liquid pool, and (e) computing the volume of the molten metal liquid. 3 figs.

  10. Low-Dimensional Network Formation in Molten Sodium Carbonate.

    Science.gov (United States)

    Wilding, Martin C; Wilson, Mark; Alderman, Oliver L G; Benmore, Chris; Weber, J K R; Parise, John B; Tamalonis, Anthony; Skinner, Lawrie

    2016-04-15

    Molten carbonates are highly inviscid liquids characterized by low melting points and high solubility of rare earth elements and volatile molecules. An understanding of the structure and related properties of these intriguing liquids has been limited to date. We report the results of a study of molten sodium carbonate (Na2CO3) which combines high energy X-ray diffraction, containerless techniques and computer simulation to provide insight into the liquid structure. Total structure factors (F(x)(Q)) are collected on the laser-heated carbonate spheres suspended in flowing gases of varying composition in an aerodynamic levitation furnace. The respective partial structure factor contributions to F(x)(Q) are obtained by performing molecular dynamics simulations treating the carbonate anions as flexible entities. The carbonate liquid structure is found to be heavily temperature-dependent. At low temperatures a low-dimensional carbonate chain network forms, at T = 1100 K for example ~55% of the C atoms form part of a chain. The mean chain lengths decrease as temperature is increased and as the chains become shorter the rotation of the carbonate anions becomes more rapid enhancing the diffusion of Na(+) ions.

  11. LIFETIME AND SPECTRAL EVOLUTION OF A MAGMA OCEAN WITH A STEAM ATMOSPHERE: ITS DETECTABILITY BY FUTURE DIRECT IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    Hamano, Keiko; Kawahara, Hajime; Abe, Yutaka [Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Onishi, Masanori [Department of Earth and Planetary Sciences, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Hashimoto, George L., E-mail: keiko@eps.s.u-tokyo.ac.jp [Department of Earth Sciences, Okayama University, 3-1-1 Tsushima-Naka, Kita, Okayama, 700-8530 (Japan)

    2015-06-20

    We present the thermal evolution and emergent spectra of solidifying terrestrial planets along with the formation of steam atmospheres. The lifetime of a magma ocean and its spectra through a steam atmosphere depends on the orbital distance of the planet from the host star. For a Type I planet, which is formed beyond a certain critical distance from the host star, the thermal emission declines on a timescale shorter than approximately 10{sup 6} years. Therefore, young stars should be targets when searching for molten planets in this orbital region. In contrast, a Type II planet, which is formed inside the critical distance, will emit significant thermal radiation from near-infrared atmospheric windows during the entire lifetime of the magma ocean. The K{sub s} and L bands will be favorable for future direct imaging because the planet-to-star contrasts of these bands are higher than approximately 10{sup −7}–10{sup −8}. Our model predicts that, in the Type II orbital region, molten planets would be present over the main sequence of the G-type host star if the initial bulk content of water exceeds approximately 1 wt%. In visible atmospheric windows, the contrasts of the thermal emission drop below 10{sup −10} in less than 10{sup 5} years, whereas those of the reflected light remain 10{sup −10} for both types of planets. Since the contrast level is comparable to those of reflected light from Earth-sized planets in the habitable zone, the visible reflected light from molten planets also provides a promising target for direct imaging with future ground- and space-based telescopes.

  12. Deep magma transport at Kilauea volcano, Hawaii

    Science.gov (United States)

    Wright, T.L.; Klein, F.W.

    2006-01-01

    The shallow part of Kilauea's magma system is conceptually well-understood. Long-period and short-period (brittle-failure) earthquake swarms outline a near-vertical magma transport path beneath Kilauea's summit to 20 km depth. A gravity high centered above the magma transport path demonstrates that Kilauea's shallow magma system, established early in the volcano's history, has remained fixed in place. Low seismicity at 4-7 km outlines a storage region from which magma is supplied for eruptions and intrusions. Brittle-failure earthquake swarms shallower than 5 km beneath the rift zones accompany dike emplacement. Sparse earthquakes extend to a decollement at 10-12 km along which the south flank of Kilauea is sliding seaward. This zone below 5 km can sustain aseismic magma transport, consistent with recent tomographic studies. Long-period earthquake clusters deeper than 40 km occur parallel to and offshore of Kilauea's south coast, defining the deepest seismic response to magma transport from the Hawaiian hot spot. A path connecting the shallow and deep long-period earthquakes is defined by mainshock-aftershock locations of brittle-failure earthquakes unique to Kilauea whose hypocenters are deeper than 25 km with magnitudes from 4.4 to 5.2. Separation of deep and shallow long-period clusters occurs as the shallow plumbing moves with the volcanic edifice, while the deep plumbing is centered over the hotspot. Recent GPS data agrees with the volcano-propagation vector from Kauai to Maui, suggesting that Pacific plate motion, azimuth 293.5?? and rate of 7.4 cm/yr, has been constant over Kilauea's lifetime. However, volcano propagation on the island of Hawaii, azimuth 325??, rate 13 cm/yr, requires southwesterly migration of the locus of melting within the broad hotspot. Deep, long-period earthquakes lie west of the extrapolated position of Kilauea backward in time along a plate-motion vector, requiring southwesterly migration of Kilauea's magma source. Assumed ages of 0

  13. Water-magma interaction and plume processes in the 2008 Okmok eruption, Alaska

    Science.gov (United States)

    Unema, Joel; Ort, Michael H.; Larsen, Jessica D; Neal, Christina; Schaefer, Janet R.

    2016-01-01

    Eruptions of similar explosivity can have divergent effects on the surroundings due to differences in the behavior of the tephra in the eruption column and atmosphere. Okmok volcano, located on Umnak Island in the eastern Aleutian Islands, erupted explosively between 12 July and 19 August 2008. The basaltic andesitic eruption ejected ∼0.24 km3dense rock equivalent (DRE) of tephra, primarily directed to the northeast of the vent area. The first 4 h of the eruption produced dominantly coarse-grained tephra, but the following 5 wk of the eruption deposited almost exclusively ash, much of it very fine and deposited as ash pellets and ashy rain and mist. Meteorological storms combined with abundant plume water to efficiently scrub ash from the eruption column, with a rapid decrease in deposit thickness with distance from the vent. Grain-size analysis shows that the modes (although not their relative proportions) are very constant throughout the deposit, implying that the fragmentation mechanisms did not vary much. Grain-shape features consistent with molten fuel-coolant interaction are common. Surface and groundwater drainage into the vents provided the water for phreatomagmatic fragmentation. The available water (water that could reach the vent area during the eruption) was ∼2.8 × 1010 kg, and the erupted magma totaled ∼7 × 1011 kg, which yield an overall water:magma mass ratio of ∼0.04, but much of the water was not interactive. Although magma flux dropped from 1 × 107 kg/s during the initial 4 h to 1.8 × 105 kg/s for the remainder of the eruption, most of the erupted material was ejected during the lower-mass-flux period due to its much greater length, and this tephra was dominantly deposited within 10 km downwind of the vent. This highlights the importance of ash scrubbing in the evaluation of hazards from explosive eruptions.

  14. Thermodynamic study of the molten salt binary system KHSO4-NaHSO4

    DEFF Research Database (Denmark)

    Eriksen, Kim Michael; Fehrmann, Rasmus; Hatem, G

    2002-01-01

    The partial molar enthalpies of mixing of NaHSO4 and KHSO4 have been measured at 528 K by dropping samples of pure compounds into molten mixtures of NaHSO4 and KHSO4 in Calvet calorimeter. From these values the molar enthalpy of mixing has been deduced.The same method has been used for the determ......The partial molar enthalpies of mixing of NaHSO4 and KHSO4 have been measured at 528 K by dropping samples of pure compounds into molten mixtures of NaHSO4 and KHSO4 in Calvet calorimeter. From these values the molar enthalpy of mixing has been deduced.The same method has been used...

  15. Sombrero uplift above the Altiplano-Puna Magma Body: evidence of a ballooning mid-crustal diapir.

    Science.gov (United States)

    Fialko, Yuri; Pearse, Jill

    2012-10-12

    The Altiplano-Puna ultralow-velocity zone in the central Andes, South America, is the largest active magma body in Earth's continental crust. Space geodetic observations reported an uplift in the Altiplano-Puna proper at a rate of ~10 mm/year; however, the nature of the inferred inflation source has been uncertain. We present data showing that the uplift has persisted at a nearly constant rate over the past two decades, and is surrounded by a broad zone of subsidence. We show that the ongoing uplift and peripheral subsidence may result from a large mid-crustal diapir fed by partial melt from the Altiplano-Puna Magma Body.

  16. Magma Dynamics in Dome-Building Volcanoes

    Science.gov (United States)

    Kendrick, J. E.; Lavallée, Y.; Hornby, A. J.; Schaefer, L. N.; Oommen, T.; Di Toro, G.; Hirose, T.

    2014-12-01

    The frequent and, as yet, unpredictable transition from effusive to explosive volcanic behaviour is common to active composite volcanoes, yet our understanding of the processes which control this evolution is poor. The rheology of magma, dictated by its composition, porosity and crystal content, is integral to eruption behaviour and during ascent magma behaves in an increasingly rock-like manner. This behaviour, on short timescales in the upper conduit, provides exceptionally dynamic conditions that favour strain localisation and failure. Seismicity released by this process can be mimicked by damage accumulation that releases acoustic signals on the laboratory scale, showing that the failure of magma is intrinsically strain-rate dependent. This character aids the development of shear zones in the conduit, which commonly fracture seismogenically, producing fault surfaces that control the last hundreds of meters of ascent by frictional slip. High-velocity rotary shear (HVR) experiments demonstrate that at ambient temperatures, gouge behaves according to Byerlee's rule at low slip velocities. At rock-rock interfaces, mechanical work induces comminution of asperities and heating which, if sufficient, may induce melting and formation of pseudotachylyte. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The bulk composition, mineralogy and glass content of the magma all influence frictional behaviour, which supersedes buoyancy as the controlling factor in magma ascent. In the conduit of dome-building volcanoes, the fracture and slip processes are further complicated: slip-rate along the conduit margin fluctuates. The shear-thinning frictional melt yields a tendency for extremely unstable slip thanks to its pivotal position with regard to the glass transition. This thermo-kinetic transition bestows the viscoelastic melt with the ability to either flow or

  17. Molten salts and nuclear energy production

    International Nuclear Information System (INIS)

    Le Brun, Christian

    2007-01-01

    Molten salts (fluorides or chlorides) were considered near the beginning of research into nuclear energy production. This was initially due to their advantageous physical and chemical properties: good heat transfer capacity, radiation insensitivity, high boiling point, wide range solubility for actinides. In addition it was realised that molten salts could be used in numerous situations: high temperature heat transfer, core coolants with solid fuels, liquid fuel in a molten salt reactor, solvents for spent nuclear solid fuel in the case of pyro-reprocessing and coolant and tritium production in the case of fusion. Molten salt reactors, one of the six innovative concepts chosen by the Generation IV international forum, are particularly interesting for use as either waste incinerators or thorium cycle systems. As the neutron balance in the thorium cycle is very tight, the possibility to perform online extraction of some fission product poisons from the salt is very attractive. In this article the most important questions that must be addressed to demonstrate the feasibility of molten salt reactor will be reviewed

  18. Electrochemistry of plutonium in molten halides

    International Nuclear Information System (INIS)

    McCurry, L.E.; Moy, G.M.M.; Bowersox, D.F.

    1987-01-01

    The electrochemistry of plutonium in molten halides is of technological importance as a method of purification of plutonium. Previous authors have reported that plutonium can be purified by electrorefining impure plutonium in various molten haldies. Work to eluciate the mechanism of the plutonium reduction in molten halides has been limited to a chronopotentiometric study in LiCl-KCl. Potentiometric studies have been carried out to determine the standard reduction potential for the plutonium (III) couple in various molten alkali metal halides. Initial cyclic voltammetric experiments were performed in molten KCL at 1100 K. A silver/silver chloride (10 mole %) in equimolar NaCl-KCl was used as a reference electrode. Working and counter electrodes were tungsten. The cell components and melt were contained in a quartz crucible. Background cyclic voltammograms of the KCl melt at the tungsten electrode showed no evidence of electroactive impurities in the melt. Plutonium was added to the melt as PuCl/sub 3/, which was prepared by chlorination of the oxide. At low concentrations of PuCl/sub 3/ in the melt (0.01-0.03 molar), no reduction wave due to the reduction of Pu(III) was observed in the voltammograms up to the potassium reduction limit of the melt. However on scan reversal after scanning into the potassium reduction limit a new oxidation wave was observed

  19. Physical properties of molten carbonate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, T.; Yanagida, M.; Tanimoto, K. [Osaka National Research Institute (Japan)] [and others

    1996-12-31

    Recently many kinds of compositions of molten carbonate electrolyte have been applied to molten carbonate fuel cell in order to avoid the several problems such as corrosion of separator plate and NiO cathode dissolution. Many researchers recognize that the addition of alkaline earth (Ca, Sr, and Ba) carbonate to Li{sub 2}CO{sub 3}-Na{sub 2}CO{sub 3} and Li{sub 2}CO{sub 3}-K{sub 2}CO{sub 3} eutectic electrolytes is effective to avoid these problems. On the other hand, one of the corrosion products, CrO{sub 4}{sup 2-} ion is found to dissolve into electrolyte and accumulated during the long-term MCFC operations. This would affect the performance of MCFC. There, however, are little known data of physical properties of molten carbonate containing alkaline earth carbonates and CrO{sub 4}{sup 2-}. We report the measured and accumulated data for these molten carbonate of electrical conductivity and surface tension to select favorable composition of molten carbonate electrolytes.

  20. The crustal magma storage system of Volcán Quizapu, Chile, and the effects of magma mixing on magma diversity

    Science.gov (United States)

    Bergantz, George W.; Cooper, Kari M.; Hildreth, Edward; Ruprecht, Phillipp

    2012-01-01

    Crystal zoning as well as temperature and pressure estimates from phenocryst phase equilibria are used to constrain the architecture of the intermediate-sized magmatic system (some tens of km3) of Volcán Quizapu, Chile, and to document the textural and compositional effects of magma mixing. In contrast to most arc magma systems, where multiple episodes of open-system behavior obscure the evidence of major magma chamber events (e.g. melt extraction, magma mixing), the Quizapu magma system shows limited petrographic complexity in two large historical eruptions (1846–1847 and 1932) that have contrasting eruptive styles. Quizapu magmas and peripheral mafic magmas exhibit a simple binary mixing relationship. At the mafic end, basaltic andesite to andesite recharge magmas complement the record from peripheral cones and show the same limited range of compositions. The silicic end-member composition is almost identical in both eruptions of Quizapu. The effusive 1846–1847 eruption records significant mixing between the mafic and silicic end-members, resulting in hybridized andesites and mingled dacites. These two compositionally simple eruptions at Volcán Quizapu present a rare opportunity to isolate particular aspects of magma evolution—formation of homogeneous dacite magma and late-stage magma mixing—from other magma chamber processes. Crystal zoning, trace element compositions, and crystal-size distributions provide evidence for spatial separation of the mafic and silicic magmas. Dacite-derived plagioclase phenocrysts (i.e. An25–40) show a narrow range in composition and limited zonation, suggesting growth from a compositionally restricted melt. Dacite-derived amphibole phenocrysts show similar restricted compositions and furthermore constrain, together with more mafic amphibole phenocrysts, the architecture of the magmatic system at Volcán Quizapu to be compositionally and thermally zoned, in which an andesitic mush is overlain by a homogeneous dacitic

  1. Imaging magma plumbing beneath Askja volcano, Iceland

    Science.gov (United States)

    Greenfield, Tim; White, Robert S.

    2015-04-01

    Volcanoes during repose periods are not commonly monitored by dense instrumentation networks and so activity during periods of unrest is difficult to put in context. We have operated a dense seismic network of 3-component, broadband instruments around Askja, a large central volcano in the Northern Volcanic Zone, Iceland, since 2006. Askja last erupted in 1961, with a relatively small basaltic lava flow. Since 1975 the central caldera has been subsiding and there has been no indication of volcanic activity. Despite this, Askja has been one of the more seismically active volcanoes in Iceland. The majority of these events are due to an extensive geothermal area within the caldera and tectonically induced earthquakes to the northeast which are not related to the magma plumbing system. More intriguing are the less numerous deeper earthquakes at 12-24km depth, situated in three distinct areas within the volcanic system. These earthquakes often show a frequency content which is lower than the shallower activity, but they still show strong P and S wave arrivals indicative of brittle failure, despite their location being well below the brittle-ductile boundary, which, in Askja is ~7km bsl. These earthquakes indicate the presence of melt moving or degassing at depth while the volcano is not inflating, as only high strain rates or increased pore fluid pressures would cause brittle fracture in what is normally an aseismic region in the ductile zone. The lower frequency content must be the result of a slower source time function as earthquakes which are both high frequency and low frequency come from the same cluster, thereby discounting a highly attenuating lower crust. To image the plumbing system beneath Askja, local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. Travel-time tables were created using a finite difference technique and the residuals were used to solve simultaneously for both the earthquake locations

  2. Illuminating magma shearing processes via synchrotron imaging

    Science.gov (United States)

    Lavallée, Yan; Cai, Biao; Coats, Rebecca; Kendrick, Jackie E.; von Aulock, Felix W.; Wallace, Paul A.; Le Gall, Nolwenn; Godinho, Jose; Dobson, Katherine; Atwood, Robert; Holness, Marian; Lee, Peter D.

    2017-04-01

    Our understanding of geomaterial behaviour and processes has long fallen short due to inaccessibility into material as "something" happens. In volcanology, research strategies have increasingly sought to illuminate the subsurface of materials at all scales, from the use of muon tomography to image the inside of volcanoes to the use of seismic tomography to image magmatic bodies in the crust, and most recently, we have added synchrotron-based x-ray tomography to image the inside of material as we test it under controlled conditions. Here, we will explore some of the novel findings made on the evolution of magma during shearing. These will include observations and discussions of magma flow and failure as well as petrological reaction kinetics.

  3. Modelization of the SECM in molten salts environment

    International Nuclear Information System (INIS)

    Lucas, M.; Slim, C.; Di Caprio, D.; Delpech, S.; Stafiej, J.

    2013-01-01

    We develop a cellular automata simulation of SECM (Scanning Electrochemical Microscopy)experiments to study corrosion in molten salt media for generation IV nuclear reactors. The electrodes used in these experiments are cylindrical glass tips with a coaxial metal wire inside. As the result of simulations we obtain the current approach curves of the electrodes with geometries characterized by several values of the ratios of glass to metal area at the tip. We compare these results with predictions of the known analytic expressions, solutions of partial differential equations for flat uniform geometry of the substrate. We present also the results for other, more complicated substrate surface geometries e. g. regular saw modulated surface, or surface obtained by an Eden model process. We show that with a simple cellular automata model we can reasonably well simulate the results of SECM setup. The stochastic resolution of the diffusion equations is made possible by the parallel code implemented on GPU

  4. Characteristics of fission product release from a molten pool

    International Nuclear Information System (INIS)

    Yun, J.I.; Suh, K.Y.; Kang, C.S.

    2001-01-01

    The volatile fission products are released from the debris pool, while the less volatile fission products tend to remain as condensed phases because of their low vapor pressure. The release of noble gases and the volatile fission products is dominated by bubble dynamics. The release of the less volatile fission products from the pool can be analyzed based on mass transport through a liquid with the convection flow. The physico-numerical models were orchestrated from existing submodels in various disciplines of engineering to estimate the released fraction of fission products from a molten pool. It was assumed that the pool has partially filled hemispherical geometry. For the high pool pressure, the diameter of the bubbles at detachment was calculated utilizing the Cole and Shulman correlation with the effect of system pressure. Sensitivity analyses were performed and results of the numerical calculations were compared with analysis results for the TMI-2 accident. (author)

  5. Pressure waves in a supersaturated bubbly magma

    Science.gov (United States)

    Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

    2011-01-01

    We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

  6. Yamato 980459: Crystallization of Martian Magnesian Magma

    Science.gov (United States)

    Koizumi, E.; Mikouchi, T.; McKay, G.; Monkawa, A.; Chokai, J.; Miyamoto, M.

    2004-01-01

    Recently, several basaltic shergottites have been found that include magnesian olivines as a major minerals. These have been called olivinephyric shergottites. Yamato 980459, which is a new martian meteorite recovered from the Antarctica by the Japanese Antarctic expedition, is one of them. This meteorite is different from other olivine-phyric shergottites in several key features and will give us important clues to understand crystallization of martian meteorites and the evolution of Martian magma.

  7. Development of viscometers for molten salts

    International Nuclear Information System (INIS)

    Hayashi, Hirokazu; Kato, Yoshio; Ogawa, Toru; Sato, Yuzuru.

    1997-06-01

    Viscometers specially designed for molten salts were made. One is a oscillating cup type and the other is a capillary type. In the case of the oscillating cup viscometer, the viscosity is determined absolutely through the period and the logarithmic decrement of oscillation with other physical parameters. The period and the logarithmic decrement are calculated from the time intervals between two photo-detectors' intercepts of the reflected laser beam. The capillary viscometer used is made of quartz and the sample is sealed under vacuum, which is placed in a transparent furnace. Efflux time is measured by direct visual observation. Cell constants are determined with distilled water as a calibrating liquid. Viscosities of molten KCl are measured with each viscometer. The differences between measured and standard values of molten KCl at several temperatures are within 5% for the oscillating cup viscometer and within 3% for the capillary viscometer. (author)

  8. Molten salt burner fuel behaviour and treatment

    International Nuclear Information System (INIS)

    Ignatiev, V.V.; Zakirov, R.Y.; Grebenkine, K.F.

    2001-01-01

    The objective of this paper is to discuss the feasibility of molten salt reactor technology for treatment of Pu, minor actinides and fission products, when the reactor and fission product clean-up unit are planned as an integral system. This contribution summarises the available R and D which led to selection of the fuel compositions for the molten salt reactor of the TRU burner type (MSB). Special characteristics of behaviour of TRUs and fission products during power operation of MSB concepts are presented. The present paper briefly reviews the processing developments underlying the prior molten salt reactor programmes and relates them to the separation requirements of the MSB concept, including the permissible range of processing cycle times and removal times. Status and development needs in the thermodynamic properties of fluorides, fission product clean-up methods and container materials compatibility with the working fluids for the fission product clean-up unit are discussed. (authors)

  9. Molten salt reactors - safety options galore

    International Nuclear Information System (INIS)

    Gat, U.; Dodds, H.L.

    1997-01-01

    Safety features and attributes of molten salt reactors (MSR) are described. The unique features of fluid fuel reactors of on-line continuous processing and the ability for so-called external cooling result in simple and safe designs with low excess reactivity, low fission product inventory, and small source term. These, in turn, make a criticality accident unlikely and reduce the severity of a loss of coolant to where they are no longer severe accidents. A melt down is not an accident for a reactor that uses molten fuel. The molten salts are stable, non-reactive and efficient heat transfer media that operate at high temperatures at low pressures and are highly compatible with selected structural materials. All these features reduce the accident plethora. Freeze valves can be used for added safety. An ultimate safe reactor (U.S.R) is described with safety features that are passive, inherent and non-tamperable (PINT)

  10. Thorium Molten-Salt Nuclear Energy Synergetics

    International Nuclear Information System (INIS)

    Furukawa, Kazuo; Lecocq, A.; Kato, Yoshio; Mitachi, Kohshi.

    1990-01-01

    In the next century, the 'fission breeder' concept will not be practical to solve the global energy problems, including environmental and North-South problems. As a new measure, a simple rational Th molten salt breeding fuel cycle system, named 'Thorium Molten-Salt Nuclear Energy Synergetics (THORIMS-NES)', which composed of simple power stations and fissile producers, is proposed. This is effective to establish the essential improvement in issues of resources, safety, power-size flexibility, anti-nuclear proliferation and terrorism, radiowaste, economy, etc. securing the simple operation, maintenance, chemical processing, and rational breeding fuel cycle. As examples, 155 MWe fuel self-sustaining power station 'FUJI-II', 7 MWe pilot-plant 'miniFUJI-II', 1 GeV-300 mA proton Accelerator Molten-Salt Breeder 'AMSB', and their combined fuel cycle system are explained. (author)

  11. Modelling of molten fuel/concrete interactions

    International Nuclear Information System (INIS)

    Muir, J.F.; Benjamin, A.S.

    1980-01-01

    A computer program modelling the interaction between molten core materials and structural concrete (CORCON) is being developed to provide quantitative estimates of fuel-melt accident consequences suitable for risk assessment of light water reactors. The principal features of CORCON are reviewed. Models developed for the principal interaction phenomena, inter-component heat transfer, concrete erosion, and melt/gas chemical reactions, are described. Alternative models for the controlling phenomenon, heat transfer from the molten pool to the surrounding concrete, are presented. These models, formulated in conjunction with the development of CORCON, are characterized by the presence or absence of either a gas film or viscous layer of molten concrete at the melt/concrete interface. Predictions of heat transfer based on these models compare favorably with available experimental data

  12. Effect of pressure on Fe3+/ΣFe ratio in a mafic magma and consequences for magma ocean redox gradients

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H. L.; Hirschmann, M. M.; Cottrell, E.; Withers, A. C.

    2017-05-01

    Experiments establishing the effect of pressure on the Fe3+/ΣFe ratio of andesitic silicate melts buffered by coexisting Ru and RuO2 were performed from 100 kPa to 7 GPa and 1400–1750 °C. Fe3+/ΣFe ratios were determined by room temperature Mössbauer spectroscopy, but corrected for the effects of recoilless fraction. Fe3+/ΣFe ratios in quenched glasses decrease with increasing pressure consistent with previous results between 100 kPa and 3 GPa (O’Neill et al., 2006), but show only small pressure effects above 5 GPa. Ratios also decrease with increasing temperature. Mössbauer hyperfine parameters indicate mean coordination of Fe3+ ions of ~5 in glasses, with no dependence on the pressure from which the glasses were quenched, but show an increase with pressure in mean coordination of Fe2+ ions, from ~5 to ~6. XANES spectra on these glasses show variations in pre-edge intensities and centroid positions that are systematic with Fe3+/ΣFe, but are displaced from those established from otherwise identical andesitic glasses quenched at 100 kPa (Zhang et al., 2016). These systematics permit construction of a new XANES calibration curve relating pre-edge sub-peak intensities to Fe3+/ΣFe applicable to high pressure glasses. Consistent with interpretations of the Mössbauer hyperfine parameters, XANES pre-edge peak features in high pressure glasses are owing chiefly to the effects of pressure on the coordination of Fe2+ ions from ~5.5 to ~6, with negligible effects evident for Fe3+ ions. We use the new data to construct a thermodynamic model relating the effects of oxygen fugacity and pressure on Fe3+/ΣFe. We apply this model to calculate variations in oxygen fugacity in isochemical (constant Fe3+/ΣFe) columns of magma representative of magma oceans, in which fO2 is fixed at the base by equilibration with molten Fe. These calculations

  13. Process for recovering tritium from molten lithium metal

    Science.gov (United States)

    Maroni, Victor A.

    1976-01-01

    Lithium tritide (LiT) is extracted from molten lithium metal that has been exposed to neutron irradiation for breeding tritium within a thermonuclear or fission reactor. The extraction is performed by intimately contacting the molten lithium metal with a molten lithium salt, for instance, lithium chloride - potassium chloride eutectic to distribute LiT between the salt and metal phases. The extracted tritium is recovered in gaseous form from the molten salt phase by a subsequent electrolytic or oxidation step.

  14. Experimental studies of actinides in molten salts

    International Nuclear Information System (INIS)

    Reavis, J.G.

    1985-06-01

    This review stresses techniques used in studies of molten salts containing multigram amounts of actinides exhibiting intense alpha activity but little or no penetrating gamma radiation. The preponderance of studies have used halides because oxygen-containing actinide compounds (other than oxides) are generally unstable at high temperatures. Topics discussed here include special enclosures, materials problems, preparation and purification of actinide elements and compounds, and measurements of various properties of the molten volts. Property measurements discussed are phase relationships, vapor pressure, density, viscosity, absorption spectra, electromotive force, and conductance. 188 refs., 17 figs., 6 tabs

  15. Experimental studies of actinides in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Reavis, J.G.

    1985-06-01

    This review stresses techniques used in studies of molten salts containing multigram amounts of actinides exhibiting intense alpha activity but little or no penetrating gamma radiation. The preponderance of studies have used halides because oxygen-containing actinide compounds (other than oxides) are generally unstable at high temperatures. Topics discussed here include special enclosures, materials problems, preparation and purification of actinide elements and compounds, and measurements of various properties of the molten volts. Property measurements discussed are phase relationships, vapor pressure, density, viscosity, absorption spectra, electromotive force, and conductance. 188 refs., 17 figs., 6 tabs.

  16. Chemistry and technology of Molten Salt Reactors - history and perspectives

    International Nuclear Information System (INIS)

    Uhlir, Jan

    2007-01-01

    Molten Salt Reactors represent one of promising future nuclear reactor concept included also in the Generation IV reactors family. This reactor type is distinguished by an extraordinarily close connection between the reactor physics and chemical technology, which is given by the specific features of the chemical form of fuel, representing by molten fluoride salt and circulating through the reactor core and also by the requirements of continuous 'on-line' reprocessing of the spent fuel. The history of Molten Salt Reactors reaches the period of fifties and sixties, when the first experimental Molten Salt Reactors were constructed and tested in ORNL (US). Several molten salt techniques dedicated to fresh molten salt fuel processing and spent fuel reprocessing were studied and developed in those days. Today, after nearly thirty years of discontinuance, a renewed interest in the Molten Salt Reactor technology is observed. Current experimental R and D activities in the area of Molten Salt Reactor technology are realized by a relatively small number of research institutions mainly in the EU, Russia and USA. The main effort is directed primarily to the development of separation processes suitable for the molten salt fuel processing and reprocessing technology. The techniques under development are molten salt/liquid metal extraction processes, electrochemical separation processes from the molten salt media, fused salt volatilization techniques and gas extraction from the molten salt medium

  17. Broadband phase difference method for ultrasonic velocimetry in molten glass

    International Nuclear Information System (INIS)

    Kikura, Hiroshige; Ihara, Tomonori

    2016-01-01

    This study aims to develop ultrasonic Doppler velocimetry in molten glass. Realization of such a technique has two difficulties: ultrasonic transmission into molten salt and Doppler signal processing. Buffer rod technique was developed in our research to transmit ultrasound into high temperature molten glass. This article discusses newly developed signal processing technique named broadband phase difference method. (J.P.N.)

  18. Refractory thermowell for continuous high temperature measurement of molten metal

    International Nuclear Information System (INIS)

    Thiesen, T.J.

    1992-01-01

    This patent describes a vessel for handling molten metal having an interior refractory lining, apparatus for continuous high temperature measurement of the molten metal. It comprises a thermowell; the thermowell containing a multiplicity of thermocouples; leads being coupled to a means for continuously indicating the temperature of the molten metal in the vessel

  19. Apparatus and Method for Increasing the Diameter of Metal Alloy Wires Within a Molten Metal Pool

    Science.gov (United States)

    Hartman, Alan D.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; King, Paul E.; Turner, Paul C.

    2002-01-29

    In a dip forming process the core material to be coated is introduced directly into a source block of coating material eliminating the need for a bushing entrance component. The process containment vessel or crucible is heated so that only a portion of the coating material becomes molten, leaving a solid portion of material as the entrance port of, and seal around, the core material. The crucible can contain molten and solid metals and is especially useful when coating core material with reactive metals. The source block of coating material has been machined to include a close tolerance hole of a size and shape to closely fit the core material. The core material moves first through the solid portion of the source block of coating material where the close tolerance hole has been machined, then through a solid/molten interface, and finally through the molten phase where the diameter of the core material is increased. The crucible may or may not require water-cooling depending upon the type of material used in crucible construction. The system may operate under vacuum, partial vacuum, atmospheric pressure, or positive pressure depending upon the type of source material being used.

  20. Partial pressures of oxygen, phosphorus and fluorine in some lunar lavas

    Science.gov (United States)

    Nash, W. P.; Hausel, W. D.

    1973-01-01

    Lunar sample 14310 is a feldspar-rich basalt which shows no evidence of shock deformation or recrystallization. Pyroxenes include Mg-rich orthopyroxene, pigeonite and augite; pyroxferroite occurs in the interstitial residuum. Plagioclase feldspars are zoned from An(96) to An(67), and variations in feldspar compositions do not necessarily indicate loss of Na during eruption of the lava. Opaque phases include ilmenite, ulvospinel, metallic iron, troilite, and schreibersite. Both whitlockite and apatite are present, and the interstitial residua contain baddeleyite, tranquillityite and barium-rich sanidine. Theoretical calculations provide estimates of partial pressures of oxygen, phosphorus, and fluorine in lunar magmas. In general, partial pressures of oxygen are restricted by the limiting assemblages of iron-wuestite and ilmenite-iron-rutile; phosphorus partial pressures are higher in lunar magmas than in terrestrial lavas. The occurrence of whitlockite indicates significantly lower fugacities of fluorine in lunar magmas than in terrestrial magmas.

  1. Oxidation State of Iron in the Izu-Bonin Arc Initial Magma and Its Influence Factors

    Science.gov (United States)

    Li, H.; Arculus, R. J.; Brandl, P. A.; Hamada, M.; Savov, I. P.; Zhu, S.; Hickey-Vargas, R.; Tepley, F. J., III; Meffre, S.; Yogodzinski, G. M.; McCarthy, A.; Barth, A. P.; Kanayama, K.; Kusano, Y.; Sun, W.

    2014-12-01

    The redox state of mantle-derived magmas is a controversial issue, especially whether island arc basalts are more oxidized than those from mid-ocean ridges. Usually, arc magmas have higher Fe3+/Fe2+ and calculated oxygen fugacity (fO2) than mid-ocean ridge basalts (MORB). It is the high fO2 of arc magma that apparently delays onset of sulfide fractionation and sequestration of precious/base metals thereby facilitating the formation of many giant gold-copper deposits typically associated with subduction zones. But due to a paucity of Fe3+/Fe2+ data for primary mantle-derived arc magmas, the cause for high fO2 of these magma types is still controversial; causes may include inter alia subduction-released oxidized material addition to the mantle wedge source of arc magma, partial melting of subducted slab, and redox changes occurring during ascent of the magma. Fortunately, IODP expedition 351 drilling at IODP Site U1438 in the Amami-Sankaku Basin of the northwestern Philipine Sea, adjacent to the proto-Izu-Bonin Arc at the Kyushu-Palau Ridge (KPR), recovered not only volcaniclastics derived from the inception of Izu-Bonin Mariana (IBM) arc in the Eocene, but also similar materials for the Arc's subsequent evolution through to the Late Oligocene and abandonment of the KPR as a remnant arc. Samples of the pre-Arc oceanic crustal basement were also recovered enabling us to determine the fO2of the mantle preceding arc inception. As the oxidation state of iron in basaltic glass directly relates to the fO2 , the Fe3+/∑Fe ratio [Fe3+/(Fe3++ Fe2+)] of basaltic glass are quantified by synchrotron-facilitated micro X-ray Absorption Near Edge Structure (XANES) spectroscopy to reflect its fO2. Fe K-edge µ-XANES spectra were recorded in fluorescence mode at Beamline 15U1, Shanghai Synchrotron Radiation Facility (SSRF). Synthetic silicate glass with known Fe3+/∑Fe ratio was used in data handling. The experimental results as well as preliminary data from IODP Expedition 351

  2. Constraint on the magma sources in Luzon Island Philippines by using P and S wave local seismic tomography

    Science.gov (United States)

    Nghia, N. C.; Huang, B. S.; Chen, P. F.

    2017-12-01

    The subduction of South China Sea beneath the Luzon Island has caused a complex setting of seismicity and magmatism because of the proposed ridge subduction and slab tearing. To constrain the validity of slab tearing induced by ridge subduction and their effect, we performed a P and S wave seismic tomography travel time inversion using LOTOS code. The dataset has been retrieved from International Seismological Centre from 1960 to 2008. A 1D velocity inverted by using VELEST with a Vp/Vs ratio of 1.74 is used as the starting input velocity for tomographic inversion. Total of 20905 P readings and 8126 S readings from 2355 earthquakes events were used to invert for velocity structure beneath Luzon Island. The horizontal tomographic results show low-velocity, high Vp/Vs regions at the shallow depth less than 50 km which are interpreted as the magmatic chambers of the volcanic system in Luzon. At the suspected region of slab tearing at 16oN to 18oN, two sources of magma have been indentified: slab window magma at shallow depth (< 50 km) and magma induced by mantle wedge partial melting from higher depth. This slab melting may have changed the composition of magmatic to become more silicic with high viscosity, which explains the volcanic gap in this region. At the region of 14oN to 15oN, large magma chambers under active volcanos are identified which explain the active volcanism in this region. Contrast to the region of slab tearing, in this region, the magma chambers are fed by only magma from partial melting of mantle wedge from the depth higher than 100 km. These observations are consistent with previous work on the slab tearing of South China Sea and the activities of volcanism in the Luzon Island.

  3. Desulfurization kinetics of molten copper by gas bubbling

    Science.gov (United States)

    Fukunaka, Y.; Nishikawa, K.; Sohn, H. S.; Asaki, Z.

    1991-02-01

    Molten copper with 0.74 wt pct sulfur content was desulfurized at 1523 K by bubbling Ar-O2 gas through a submerged nozzle. The reaction rate was significantly influenced not only by the oxygen partial pressure but also by the gas flow rate. Little evolution of SO2 gas was observed in the initial 10 seconds of the oxidation; however, this was followed by a period of high evolution rate of SO2 gas. The partial pressure of SO2 gas decreased with further progress of the desulfurization. The effect of the immersion depth of the submerged nozzle was negligible. The overall reaction is decomposed to two elementary reactions: the desulfurization and the dissolution rate of oxygen. The assumptions were made that these reactions are at equilibrium and that the reaction rates are controlled by mass transfer rates within and around the gas bubble. The time variations of sulfur and oxygen contents in the melt and the SO2 partial pressure in the off-gas under various bubbling conditions were well explained by the mathematical model combined with the reported thermodynamic data of these reactions. Based on the present model, it was anticipated that the oxidation rate around a single gas bubble was mainly determined by the rate of gas-phase mass transfer, but all oxygen gas blown into the melt was virtually consumed to the desulfurization and dissolution reactions before it escaped from the melt surface.

  4. Electrochemical behavior of molten fluoride-water system

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Toshihide; Ito, Yasuhiko; Ishikawa, Takayasu; Oishi, Jun

    1984-11-01

    The cathodic behavior of a molten fluoride-water system was investigated by the potential sweep method. LiF-KF-NaF eutectic melt was used as an electrolyte and HF-H/sub 2/O gas mixture with Ar as a carrier was bubbled into it. Gold wire was used as a working electrode. The peak currents due to the reduction of HF and H/sub 2/O were clearly observed. The relations between peak currents and the square roots of the scanning rates were linear, strongly suggesting that the reduction reactions of the HF and H/sub 2/O dissolved in the melt were diffusion controlled. From the linearity of the relations between peak currents and partial pressures of HF and H/sub 2/O in the low partial pressure region, it was concluded that the concentrations of HF and H/sub 2/O in a fluoride melt are proportional to the partial pressure of each gas. The peak current due to the reduction of OH/sup -/ ion could not be observed, though a clear peak current was observed when OH/sup -/ ion was added to the melt and a cathodic scan was applied immediately. This indicates that OH/sup -/ ion is unstable in a fluoride melt under HF-H/sub 2/O atmosphere.

  5. Temporal constraints on magma generation and differentiation in a continental volcano: Buckland, eastern Australia

    Science.gov (United States)

    Crossingham, Tracey J.; Ubide, Teresa; Vasconcelos, Paulo M.; Knesel, Kurt M.; Mallmann, Guilherme

    2018-03-01

    The eastern margin of the Australian continent hosts a large number of Cenozoic intraplate volcanoes along a 2000 km long track. Here, we study mafic lavas from the Buckland volcano, Queensland, located in the northern (older) segment of this track, to assess magma generation and differentiation through time. The rocks are aphanitic to microporphyritic basalts, trachy-basalts and basanites. Incompatible element geochemistry together with Sr-Nd-Pb isotope ratios indicate that magmas formed from an enriched mantle I (EMI)-like garnet-bearing source with variable degrees of crustal contamination. Whole rock elemental variations suggest fractionation of olivine, plagioclase, clinopyroxene and/or magnetite. There is no petrographic or geochemical evidence of magma mixing in the studied rocks (e.g., lack of recycled minerals), suggesting a relatively quick ascent from the source to the surface without major storage at shallow levels. 40Ar/39Ar geochronology reveals two stages of volcanism: 30.3 ± 0.1 Ma and 27.4 ± 0.2 Ma. The Old Buckland (30.3 ± 0.1 Ma) melts have negative K anomalies, and incompatible element ratios suggest the occurrence of residual hydrous minerals in a metasomatised mantle source. We therefore infer that at the onset of volcanism, deep-mantle-derived magmas interacted with metasomatised sub-continental lithospheric mantle (SCLM). Major and trace element data, clinopyroxene thermobarometry and thermodynamic modelling indicate magma evolution by assimilation and fractional crystallisation (AFC) during ascent through the crust. Following a hiatus in volcanic activity of 2.5 Ma, eruption of Young Buckland (27.4 ± 0.2 Ma) lavas marked a shift towards more alkaline compositions. Trace element compositions indicate lower degrees of partial melting and a lack of interaction with metasomatic components. Young Buckland lavas become progressively more SiO2-saturated up stratigraphy, suggesting an increase in the degree of partial melting with time. Young

  6. Combined system of accelerator molten-salt breeder (AMSB) apd molten-salt converter reactor (MSCR)

    International Nuclear Information System (INIS)

    Furukawa, K.; Kato, Y.; Ohmichi, T.; Ohno, H.

    1983-01-01

    A design and research program is discUssed of the development of accelerator molten-salt breeder (AMSB) consisting of a proton accelerator and a molten fluoride target. The target simultaneously serves as a blanket for fissionable material prodUction. An addition of some amoUnt of fissile nuclides to a melt expands the AMSB potentialities as the fissionable material production increases and the energy generation also grows up to the level of self-provision. Besides the blanket salts may be used as nuclear fuel for molten-salt converter reactor (MSCR). The combined AM SB+MSCR system has better parameters as compared to other breeder reactors, molten-salt breeder reactors (MSBR) included

  7. Density of alkaline magmas at crustal and upper mantle conditions by X-ray absorption

    Science.gov (United States)

    Seifert, R.; Malfait, W.; Petitgirard, S.; Sanchez-Valle, C.

    2011-12-01

    Silicate melts are essential components of igneous processes and are directly involved in differentiation processes and heat transfer within the Earth. Studies of the physical properties of magmas (e.g., density, viscosity, conductivity, etc) are however challenging and experimental data at geologically relevant pressure and temperature conditions remain scarce. For example, there is virtually no data on the density at high pressure of alkaline magmas (e.g., phonolites) typically found in continental rift zone settings. We present in situ density measurements of alkaline magmas at crustal and upper mantle conditions using synchrotron X-ray absorption. Measurements were conducted on ID27 beamline at ESRF using a panoramic Paris-Edinburgh Press (PE Press). The starting material is a synthetic haplo-phonolite glass similar in composition to the Plateau flood phonolites from the Kenya rift [1]. The glass was synthesized at 1673 K and 2.0 GPa in a piston-cylinder apparatus at ETH Zurich and characterized using EPMA, FTIR and density measurements. The sample contains less than 200 ppm water and is free of CO2. Single-crystal diamond cylinders (Øin = 0.5 mm, height = 1 mm) were used as sample containers and placed in an assembly formed by hBN spacers, a graphite heater and a boron epoxy gasket [2]. The density was determined as a function of pressure (1.0 to 3.1 GPa) and temperature (1630-1860 K) from the X-ray absorption contrast at 20 keV between the sample and the diamond capsule. The molten state of the sample during the data collection was confirmed by X-ray diffraction measurements. Pressure and temperature were determined simultaneously from the equation of state of hBN and platinum using the the double isochor method [3].The results are combined with available density data at room conditions to derive the first experimental equation of state (EOS) of phonolitic liquids at crustal and upper mantle conditions. We will compare our results with recent reports of the

  8. Recent electroanalytical studies in molten fluorides

    International Nuclear Information System (INIS)

    Manning, D.L.; Mamantov, G.

    1976-01-01

    This paper summarizes the voltametric and chronopotentiometric studies of Bi, Fe, Te, oxide and U(IV)/U(III) ratio determinations in molten LiF--BeF 2 --ThF 4 (72-16-12 mole percent) and LiF--BeF 2 --ZrF 4 (65.6-29.4-5.0 mole percent). 54 references, 11 figures

  9. Investigation of molten salt fast reactor

    International Nuclear Information System (INIS)

    Kubota, Kenichi; Konomura, Mamoru

    2002-01-01

    On survey research for practicability strategy of fast reactor (FR) (phase 1), to extract future practicability image candidates of FR from wide options, in addition to their survey and investigation objects of not only solid fuel reactors of conventional research object but also molten salt reactor as a flowing fuel reactor, investigation on concept of molten salt FR plant was carried out. As a part of the first step of the survey research for practicability strategy, a basic concept on plant centered at nuclear reactor facility using chloride molten salt reactor capable of carrying out U-Pu cycle was examined, to perform a base construction to evaluate economical potential for a practical FBR. As a result, a result could be obtained that because of inferior fuel inventory and heat transmission to those in Na cooling reactor in present knowledge, mass of reactor vessel and intermediate heat exchanger were to widely increased to expect reduction of power generation unit price even on considering cheapness of its fuel cycle cost. Therefore, at present step further investigation on concept design of the chloride molten salt reactor plant system is too early in time, and it is at a condition where basic and elementary researches aiming at upgrading of economical efficiency such as wide reduction of fuel inventory, a measure expectable for remarkable rationalization effect of reprocessing system integrating a reactor to a processing facility, and so on. (G.K.)

  10. Galvanic high energy cells with molten electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Borger, W.; Kappus, W.; Kunze, D.; Laig-Hoerstebrock, H.; Panesar, H.; Sterr, G.

    1981-01-01

    To develop a galvanic cell with molten salt electrolyte for electric vehicle propulsion and load leveling as well as to fabricate ten prototype cells with a capacity of at least 150 Ah (5 hour rate) and an energy density of 80 Wh/kg was the objective of this project.

  11. Chemical Zoning of Feldspars in Lunar Granitoids: Implications for the Origins of Lunar Silicic Magmas

    Science.gov (United States)

    Mills, R. D; Simon, J. I.; Alexander, C.M. O'D.; Wang, J.; Christoffersen, R.; Rahman, Z..

    2014-01-01

    Fine-scale chemical and textural measurements of alkali and plagioclase feldspars in the Apollo granitoids (ex. Fig. 1) can be used to address their petrologic origin(s). Recent findings suggest that these granitoids may hold clues of global importance, rather than of only local significance for small-scale fractionation. Observations of morphological features that resemble silicic domes on the unsampled portion of the Moon suggest that local, sizable net-works of high-silica melt (>65 wt % SiO2) were present during crust-formation. Remote sensing data from these regions suggest high concentrations of Si and heat-producing elements (K, U, and Th). To help under-stand the role of high-silica melts in the chemical differentiation of the Moon, three questions must be answered: (1) when were these magmas generated?, (2) what was the source material?, and (3) were these magmas produced from internal differentiation. or impact melting and crystallization? Here we focus on #3. It is difficult to produce high-silica melts solely by fractional crystallization. Partial melting of preexisting crust may therefore also have been important and pos-sibly the primary mechanism that produced the silicic magmas on the Moon. Experimental studies demonstrate that partial melting of gabbroic rock under mildly hydrated conditions can produce high-silica compositions and it has been suggested by that partial melting by basaltic underplating is the mechanism by which high-silica melts were produced on the Moon. TEM and SIMS analyses, coordinated with isotopic dating and tracer studies, can help test whether the minerals in the Apollo granitoids formed in a plutonic setting or were the result of impact-induced partial melting. We analyzed granitoid clasts from 3 Apollo samples: polymict breccia 12013,141, crystalline-matrix breccia 14303,353, and breccia 15405,78

  12. The influence of magma viscosity on convection within a magma chamber

    Science.gov (United States)

    Schubert, M.; Driesner, T.; Ulmer, P.

    2012-12-01

    Magmatic-hydrothermal ore deposits are the most important sources of metals like Cu, Mo, W and Sn and a major resource for Au. It is well accepted that they are formed by the release of magmatic fluids from a batholith-sized magma body. Traditionally, it has been assumed that crystallization-induced volatile saturation (called "second boiling") is the main mechanism for fluid release, typically operating over thousands to tens of thousands of years (Candela, 1991). From an analysis of alteration halo geometries caused by magmatic fluids, Cathles and Shannon (2007) suggested much shorter timescales in the order of hundreds of years. Such rapid release of fluids cannot be explained by second boiling as the rate of solidification scales with the slow conduction of heat away from the system. However, rapid fluid release is possible if convection is assumed within the magma chamber. The magma would degas in the upper part of the magma chamber and volatile poor magma would sink down again. Such, the rates of degassing can be much higher than due to cooling only. We developed a convection model using Navier-Stokes equations provided by the computational fluid dynamics platform OpenFOAM that gives the possibility to use externally derived meshes with complex (natural) geometries. We implemented a temperature, pressure, composition and crystal fraction dependent viscosity (Ardia et al., 2008; Giordano et al., 2008; Moore et al., 1998) and a temperature, pressure, composition dependent density (Lange1994). We found that the new viscosity and density models strongly affect convection within the magma chamber. The dependence of viscosity on crystal fraction has a particularly strong effect as the steep viscosity increase at the critical crystal fraction leads to steep decrease of convection velocity. As the magma chamber is cooling from outside to inside a purely conductive layer is developing along the edges of the magma chamber. Convection continues in the inner part of the

  13. Thorium Molten Salt Nuclear Energy Synergetic System (THORIMS-NES)

    International Nuclear Information System (INIS)

    Yoshioka, Ritsuo; Mitachi, Koshi

    2013-01-01

    The authors have been promoting nuclear energy technology based on thorium molten salt as Thorium Molten Salt Nuclear Energy Synergetic System (THORIMS-NES). This system is a combination of fission power reactor of Molten Salt Reactor (MSR), and Accelerator Molten Salt Breeder (AMSB) for production of fissile 233 U with connecting chemical processing facility. In this paper, concept of THORIMS-NES, advantages of thorium and molten salt recent MSR design results such as FUJI-U3 using 233 U fuel, FUJI-Pu, large sized super-FUJI, pilot plant miniFUJI, AMSB, and chemical processing facility are described. (author)

  14. Molten salt: Corrosion problems and electrometallurgy in nuclear applications

    International Nuclear Information System (INIS)

    Santarini, G.

    1981-01-01

    A bibliographic survey is given of corrosion problems and electrometallurgical problems of molten salt in nuclear reactor applications. Due to the high potential to be achieved, their high ionic conductivity and the rapidity of reactions in a molten salt atmosphere, molten salts are interesting solvents for various electrometallurgical processes. Another important field of application is in the separation or electrolytical refining of various metals (Be, U, Pu, Th, Hf, Zr). However, these very characteristics of molten salts may also cause serious corrosion problems. Results obtained for the molten-salt reactor and the different causes of corrosion are reviewed an possible countermeasures analyzed. (orig.)

  15. Towards a comprehensive classification of igneous rocks and magmas

    Science.gov (United States)

    Middlemost, Eric A. K.

    1991-08-01

    The IUGS Subcommission on the Systematics of Igneous Rocks has recently published an excellent book on the classification of these rocks. This event has shifted the vexed question of classification towards the top of the agenda in igneous petrology. Over the years the Subcommission has used many different criteria to establish the positions of the boundaries between the various common igneous rocks. It now has to adopt a holistic approach and develop a comprehensive, coherent classification that is purged of all the minor anomalies that arise between the various classifications that it has approved. It is appreciated that the Subcommission's classification was never intended to have any genetic implications; however, it is suggested that an ideal classification should he presented in such a way that it is able to group rocks into an order that directs attention to petrogenetic relationships between individual rocks and larger groups of rocks. Unfortunately, many of the Subcommission's definitions are Earth chauvinistic; for example, igneous rocks are defined as being those rocks that solidified from a molten state either within or on the surface of the Earth. Nowhere in the book is it acknowledged that during the past 20 years, while the Subcommission has been framing its many recommendations, a whole new science of planetary petrology has subsumed classical petrology. In any new edition of the book, the Subcommission should acknowledge that rocks are essentially the solid materials of which planets, natural satellites and other broadly similar cosmic bodies are made. The Subcommission should also explicitly recognise that igneous rocks can be divided into either a main sequence of essentially common rocks or a number of supplementary clans of special rocks that evolved outside the main sequence. It is hoped that in the near future the Subcommission will rescind its recommendation that the TAS classification should be regarded as an adjunct to its more traditional

  16. Barium isotope geochemistry of subduction-zone magmas

    Science.gov (United States)

    Yu, H.; Nan, X.; Huang, J.; Wörner, G.; Huang, F.

    2017-12-01

    Subduction zones are crucial tectonic setting to study material exchange between crust and mantle, mantle partial melting with fluid addition, and formation of ore-deposits1-3. The geochemical characteristics of arc lavas from subduction zones are different from magmas erupted at mid-ocean ridges4, because there are addition of fluids/melts from subducted AOC and its overlying sediments into their source regions in the sub-arc mantle4. Ba is highly incompatible during mantle melting5, and it is enriched in crust (456 ppm)6 relative to the mantle (7.0 ppm)7. The subducted sediments are also enriched in Ba (776 ppm of GLOSS)8. Moreover, because Ba is fluid soluble during subduction, it has been used to track contributions of subduction-related fluids to arc magmas9 or recycled sediments to the mantle10-11. To study the Ba isotope fractionation behavior during subduction process, we analyzed well-characterized, chemically-diverse arc lavas from Central American, Kamchatka, Central-Eastern Aleutian, and Southern Lesser Antilles. The δ137/134Ba of Central American arc lavas range from -0.13 to 0.24‰, and have larger variation than the arc samples from other locations. Except one sample from Central-Eastern Aleutian arc with obviously heavy δ137/134Ba values (0.27‰), all other samples from Kamchatka, Central-Eastern Aleutian, Southern Lesser Antilles arcs are within the range of OIB. The δ137/134Ba is not correlated with the distance to trench, partial melting degrees (Mg#), or subducting slab-derived components. The samples enriched with heavy Ba isotopes have low Ba contents, indicating that Ba isotopes can be fractionated at the beginning of dehydration process with small amount of Ba releasing to the mantle wedge. With the dehydration degree increasing, more Ba of the subducted slab can be added to the source of arc lavas, likely homogenizing the Ba isotope signatures. 1. Rudnick, R., 1995 Nature; 2. Tatsumi, Y. & Kogiso, T., 2003; 3. Sun, W., et al., 2015 Ore

  17. Computer simulation on molten ionic salts

    International Nuclear Information System (INIS)

    Kawamura, K.; Okada, I.

    1978-01-01

    The extensive advances in computer technology have since made it possible to apply computer simulation to the evaluation of the macroscopic and microscopic properties of molten salts. The evaluation of the potential energy in molten salts systems is complicated by the presence of long-range energy, i.e. Coulomb energy, in contrast to simple liquids where the potential energy is easily evaluated. It has been shown, however, that no difficulties are encountered when the Ewald method is applied to the evaluation of Coulomb energy. After a number of attempts had been made to approximate the pair potential, the Huggins-Mayer potential based on ionic crystals became the most often employed. Since it is thought that the only appreciable contribution to many-body potential, not included in Huggins-Mayer potential, arises from the internal electrostatic polarization of ions in molten ionic salts, computer simulation with a provision for ion polarization has been tried recently. The computations, which are employed mainly for molten alkali halides, can provide: (1) thermodynamic data such as internal energy, internal pressure and isothermal compressibility; (2) microscopic configurational data such as radial distribution functions; (3) transport data such as the diffusion coefficient and electrical conductivity; and (4) spectroscopic data such as the intensity of inelastic scattering and the stretching frequency of simple molecules. The computed results seem to agree well with the measured results. Computer simulation can also be used to test the effectiveness of a proposed pair potential and the adequacy of postulated models of molten salts, and to obtain experimentally inaccessible data. A further application of MD computation employing the pair potential based on an ionic model to BeF 2 , ZnCl 2 and SiO 2 shows the possibility of quantitative interpretation of structures and glass transformation phenomena

  18. Cost-benefit analyses for the development of magma power

    International Nuclear Information System (INIS)

    Haraden, John

    1992-01-01

    Magma power is the potential generation of electricity from shallow magma bodies in the crust of the Earth. Considerable uncertainty still surrounds the development of magma power, but most of that uncertainty may be eliminated by drilling the first deep magma well. The uncertainty presents no serious impediments to the private drilling of the well. For reasons unrelated to the uncertainty, there may be no private drilling and there may be justification for public drilling. In this paper, we present cost-benefit analyses for private and public drilling of the well. Both analyses indicate there is incentive for drilling. (Author)

  19. Experimental Constraints on a Vesta Magma Ocean

    Science.gov (United States)

    Hoff, C.; Jones, J. H.; Le, L.

    2014-01-01

    A magma ocean model was devised to relate eucrites (basalts) and diogenites (orthopyroxenites), which are found mixed together as clasts in a suite of polymict breccias known as howardites. The intimate association of eucritic and diogenitic clasts in howardites argues strongly that these three classes of achondritic meteorites all originated from the same planetoid. Reflectance spectral evidence (including that from the DAWN mission) has long suggested that Vesta is indeed the Eucrite Parent Body. Specifically, the magma ocean model was generated as follows: (i) the bulk Vesta composition was taken to be 0.3 CV chondrite + 0.7 L chondrite but using only 10% of the Na2O from this mixture; (ii) this composition is allowed to crystallize at 500 bar until approx. 80% of the system is solid olivine + low-Ca pyroxene; (iii) the remaining 20% liquid crystallizes at one bar from 1250C to 1110C, a temperature slightly above the eucrite solidus. All crystallization calculations were performed using MELTS. In this model, diogenites are produced by cocrystallization of olivine and pyroxene in the >1250C temperature regime, with Main Group eucrite liquids being generated in the 1300-1250C temperature interval. Low-Ca pyroxene reappears at 1210C in the one-bar calculations and fractionates the residual liquid to produce evolved eucrite compositions (Stannern Trend). We have attempted to experimentally reproduce the magma ocean. In the MELTS calculation, the change from 500 bar to one bar results in a shift of the olivine:low-Ca pyroxene boundary so that the 1250C liquid is now in the olivine field and, consequently, olivine should be the first-crystallizing phase, followed by low-Ca pyroxene at 1210C, and plagioclase at 1170C. Because at one bar the olivine:low-Ca pyroxene boundary is a peritectic, fractional crystallization of the 1210C liquid proceeds with only pyroxene crystallization until plagioclase appears. Thus, the predictions of the MELTS calculation are clear and

  20. Experimental Study of Lunar and SNC Magmas

    Science.gov (United States)

    Rutherford, Malcolm J.

    1998-01-01

    The research described in this progress report involved the study of petrological, geochemical and volcanic processes that occur on the Moon and the SNC parent body, generally accepted to be Mars. The link between these studies is that they focus on two terrestrial-type parent bodies somewhat smaller than earth, and the fact that they focus on the role of volatiles in magmatic processes and on processes of magma evolution on these planets. The work on the lunar volcanic glasses has resulted in some exciting new discoveries over the years of this grant. We discovered small metal blebs initially in the Al5 green glass, and determined the significant importance of this metal in fixing the oxidation state of the parent magma (Fogel and Rutherford, 1995). More recently, we discovered a variety of metal blebs in the Al7 orange glass. Some of these Fe-Ni metal blebs were in the glass; others were in olivine phenocrysts. The importance of these metal spheres is that they fix the oxidation state of the parent magma during the eruption, and also indicate changes during the eruption (Weitz et al., 1997) They also yield important information about the composition of the gas phase present, the gas which drove the lunar fire-fountaining. One of the more exciting and controversial findings in our research over the past year has been the possible fractionation of H from D during shock (experimental) of hornblende bearing samples (Minitti et al., 1997). This research is directed at explaining some of the low H2O and high D/H observed in hydrous phases in the SNC meteorites.

  1. Interactions between magma and the lithospheric mantle during Cenozoic rifting in Central Europe

    Science.gov (United States)

    Meyer, Romain; Elkins-Tanton, Linda T.

    2010-05-01

    During the Cenozoic, extensive intraplate volcanic activity occurred throughout Central Europe. Volcanic eruptions extend over France (the Massif Central), central Germany (Eifel, Vogelsberg, Rhön; Heldburg), the Czech Republic (the Eger graben) and SW Poland (Lower Silesia), a region ~1,200 km wide. The origin of this predominantly alkaline intraplate magmatism is often genetically linked to one or several mantle plumes, but there is no convincing evidence for this. We have measured Pb isotope ratios, together with major and trace elements, in a representative set of mafic to felsic igneous rocks from the intra-plate Cenozoic Rhön Mts. and the Heldburg dike swarm in order to gain insight into the melting source and petrogenetic history of these melts. Three different mafic rock types (tholeiitic basalt, alkali basalt, basanite) were distinguished based on petrography and geochemistry within the investigated areas. Except for the lherzolite-bearing phonolite from the Veste Heldburg all other evolved magmas are trachytes. REE geochemistry and calculated partial melting modeling experiments for the three mafic magma types point to different degrees of partial melting in a garnet-bearing mantle source. In addition a new version of the ternary Th-Hf-Ta diagram is presented in this study as a useful petrological tool. This diagram is not only able to define potentially involved melting source end-members (e.g. asthenosphere, sub-continental lithospheric mantle and continental crust) but also interactions between these members are illustrated. An advantage of this diagram compared to partial melting degree sensitive multi-element diagrams is that a ternary diagram is a closed system. An earlier version of this diagram has been recently used to establish the nature and extent of crust mantle melt interaction of volcanic rifted margins magmas (Meyer et al. 2009). The Th-Hf-Ta geochemistry of the investigated magmas is similar to spinel and garnet xenoliths from different

  2. Feet sunk in molten aluminium: The burn and its prevention.

    Science.gov (United States)

    Alonso-Peña, David; Arnáiz-García, María Elena; Valero-Gasalla, Javier Luis; Arnáiz-García, Ana María; Campillo-Campaña, Ramón; Alonso-Peña, Javier; González-Santos, Jose María; Fernández-Díaz, Alaska Leonor; Arnáiz, Javier

    2015-08-01

    Nowadays, despite improvements in safety rules and inspections in the metal industry, foundry workers are not free from burn accidents. Injuries caused by molten metals include burns secondary to molten iron, aluminium, zinc, copper, brass, bronze, manganese, lead and steel. Molten aluminium is one of the most common causative agents of burns (60%); however, only a few publications exist concerning injuries from molten aluminium. The main mechanisms of lesion from molten aluminium include direct contact of the molten metal with the skin or through safety apparel, or when the metal splash burns through the pants and rolls downward along the leg. Herein, we report three cases of deep dermal burns after 'soaking' the foot in liquid aluminium and its evolutive features. This paper aims to show our experience in the management of burns due to molten aluminium. We describe the current management principles and the key features of injury prevention. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

  3. Special relativity derived from spacetime magma.

    Science.gov (United States)

    Greensite, Fred

    2014-01-01

    We present a derivation of relativistic spacetime largely untethered from specific physical considerations, in constrast to the many physically-based derivations that have appeared in the last few decades. The argument proceeds from the inherent magma (groupoid) existing on the union of spacetime frame components [Formula: see text] and Euclidean [Formula: see text] which is consistent with an "inversion symmetry" constraint from which the Minkowski norm results. In this context, the latter is also characterized as one member of a class of "inverse norms" which play major roles with respect to various unital [Formula: see text]-algebras more generally.

  4. Special relativity derived from spacetime magma.

    Directory of Open Access Journals (Sweden)

    Fred Greensite

    Full Text Available We present a derivation of relativistic spacetime largely untethered from specific physical considerations, in constrast to the many physically-based derivations that have appeared in the last few decades. The argument proceeds from the inherent magma (groupoid existing on the union of spacetime frame components [Formula: see text] and Euclidean [Formula: see text] which is consistent with an "inversion symmetry" constraint from which the Minkowski norm results. In this context, the latter is also characterized as one member of a class of "inverse norms" which play major roles with respect to various unital [Formula: see text]-algebras more generally.

  5. Dynamics of differentiation in magma reservoirs

    Science.gov (United States)

    Jaupart, Claude; Tait, Stephen

    1995-09-01

    In large magma chambers, gradients of temperature and composition develop due to cooling and to fractional crystallization. Unstable density differences lead to differential motions between melt and crystals, and a major goal is to explain how this might result in chemical differentiation of magma. Arriving at a full description of the physics of crystallizing magma chambers is a challenge because of the large number of processes potentially involved, the many coupled variables, and the different geometrical shapes. Furthermore, perturbations are caused by the reinjection of melt from a deep source, eruption to the Earth's surface, and the assimilation of country rock. Physical models of increasing complexity have been developed with emphasis on three fundamental approaches. One is, given that large gradients in temperature and composition may occur, to specify how to apply thermodynamic constraints so that coexisting liquid and solid compositions may be calculated. The second is to leave the differentiation trend as the solution to be found, i.e., to specify how cooling occurs and to predict the evolution of the composition of the residual liquid and of the solid forming. The third is to simplify the physics so that the effects of coupled heat and mass transfer may be studied with a reduced set of variables. The complex shapes of magma chambers imply that boundary layers develop with density gradients at various angles to gravity, leading to various convective flows and profiles qf liquid stratification. Early studies were mainly concerned with describing fluid flow in the liquid interior of large reservoirs, due to gradients developed at the margins. More recent work has focused on the internal structure and flow field of boundary layers and in particular on the gradients of solid fraction and interstitial melt composition which develop within them. Crystal settling may occur in a surprisingly diverse range of regimes and may lead to intermittent deposition

  6. Electrochemical reduction behavior of simplified simulants of vitrified radioactive waste in molten CaCl2

    Science.gov (United States)

    Katasho, Yumi; Yasuda, Kouji; Nohira, Toshiyuki

    2018-05-01

    The electrochemical reduction of two types of simplified simulants of vitrified radioactive waste, simulant 1 (glass component only: SiO2, B2O3, Na2O, Al2O3, CaO, Li2O, and ZnO) and simulant 2 (also containing long-lived fission product oxides, ZrO2, Cs2O, PdO, and SeO2), was investigated in molten CaCl2 at 1103 K. The behavior of each element was predicted from the potential-pO2- diagram constructed from thermodynamic data. After the immersion of simulant 1 into molten CaCl2 without electrolysis, the dissolution of Na, Li, and Cs was confirmed by inductively coupled plasma atomic emission spectrometry and mass spectrometry analysis of the samples. The scanning electron microscopy/energy dispersive X-ray and X-ray diffraction analyses of simulants 1 and 2 electrolyzed at 0.9 V vs. Ca2+/Ca confirmed that most of SiO2 had been reduced to Si. After the electrolysis of simulants 1 and 2, Al, Zr, and Pd remained in the solid phase. In addition, SeO2 was found to remain partially in the solid phase and partially evaporate, although a small quantity dissolved into the molten salt.

  7. Symbiotic molten-salt systems coupled with accelerator molten-salt breeder (AMSB) or inertial-confined fusion hybrid molten-salt breeder (IHMSB) and their comparison

    International Nuclear Information System (INIS)

    Furukawa, K.

    1984-01-01

    Two types of breeder systems are proposed. One is the combined system of Accelerator Molten-Salt Breeder (AMSB) and Molten-Salt Converter Reactor (MSCR), and the other is the combined system of Inertial-confined Fusion Hybrid Molten-Salt Breeder (IHMSB) and modified MSCR. Both apply the molten-fluorides and have technically deep relations. AMSB would be much simpler and have already high technical feasibility. This will become economical the Th breeder system having a doubling time shorter than ten years and distributing any size of power stations MSCR. (orig.) [de

  8. Diffusive exchange of trace elements between basaltic-andesite and dacitic melt: Insights into potential metal fractionation during magma mixing

    Science.gov (United States)

    Fiege, A.; Ruprecht, P.; Simon, A. C.; Holtz, F.

    2017-12-01

    Mafic magma recharge is a common process that triggers physical and chemical mixing in magmatic systems and drives their evolution, resulting in, e.g., hybridization and volcanic eruptions. Once magma-magma contact is initiated, rapid heat-flux commonly leads to the formation of a cooling-induced crystal mush on the mafic side of the interface. Here, on a local scale (µm to cm), at the magma-magma interface, melt-melt diffusive exchange is required to approach equilibrium. Significant chemical potential gradients drive a complex, multi-element mass flux between the two systems (Liang, 2010). This diffusive-equilibration often controls crystal dissolution rates within the boundary layers and, thus, the formation of interconnected melt or fluid networks. Such networks provide important pathways for the transport of volatiles and trace metals from the mafic recharge magma to the felsic host magma, where the latter may feed volcanic activities and ore deposits. While major element diffusion in silicate melts is mostly well understood, even in complex systems, the available data for many trace element metals are limited (Liang, 2010; Zhang et al., 2010). Differences in diffusivity in a dynamic, mixing environment can cause trace element fractionation, in particular during crystallization and volatile exsolution and separation. This may affect trace element signatures in phenocrysts and magmatic volatile phases that can form near a magma-magma boundary. As a result, the chemistry of volcanic gases and magmatic-hydrothermal ore deposits may be partially controlled by such mixing phenomena. We performed melt-melt diffusion-couple experiments at 150 MPa, 1100°C, FMQ, FMQ+1 and FMQ+3 (FMQ: fayalite-magnetite-quartz oxygen fugacity buffer). Hydrated, sulfur-bearing cylinders of dacite and basaltic andesite were equilibrated for up to 20 h. Major and trace element gradients were measured by using laser-ablation ICP-MS and electron microprobe analyses. The results we will

  9. Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

    Science.gov (United States)

    Stoppa, Francesco; Principe, Claudia; Schiazza, Mariangela; Liu, Yu; Giosa, Paola; Crocetti, Sergio

    2017-03-01

    Vesuvius is a high-risk volcano and the 1631 Plinian eruption is a reference event for the next episode of explosive unrest. A complete stratigraphic and petrographic description of 1631 pyroclastics is given in this study. During the 1631 eruption a phonolite was firstly erupted followed by a tephritic phonolite and finally a phonolitic tephrite, indicating a layered magma chamber. We suggest that phonolitic basanite is a good candidate to be the primitive parental-melt of the 1631 eruption. Composition of apatite from the 1631 pyroclastics is different from those of CO2-rich melts indicating negligible CO2 content during magma evolution. Cross checking calculations, using PETROGRAPH and PELE software, accounts for multistage evolution up to phonolite starting from a phonolitic basanite melt similar to the Vesuvius medieval lavas. The model implies crystal settling of clinopyroxene and olivine at 6 kbar and 1220°C, clinopyroxene plus leucite at a pressure ranging from 2.5 to 0.5 kbar and temperature ranging from 1140 to 940°C. Inside the phonolitic magma chamber K-feldspar and leucite would coexist at a temperature ranging from from 940 to 840°C and at a pressure ranging from 2.5 to0.5 kbar. Thus crystal fractionation is certainly a necessary and probably a sufficient condition to evolve the melt from phono tephritic to phonolitic in the 1631 magma chamber. We speculate that phonolitic tephrite magma refilling from deeper levels destabilised the chamber and triggered the eruption, as testified by the seismic precursor phenomena before 1631 unrest.

  10. Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

    Directory of Open Access Journals (Sweden)

    Stoppa Francesco

    2017-03-01

    Full Text Available Vesuvius is a high-risk volcano and the 1631 Plinian eruption is a reference event for the next episode of explosive unrest. A complete stratigraphic and petrographic description of 1631 pyroclastics is given in this study. During the 1631 eruption a phonolite was firstly erupted followed by a tephritic phonolite and finally a phonolitic tephrite, indicating a layered magma chamber. We suggest that phonolitic basanite is a good candidate to be the primitive parental-melt of the 1631 eruption. Composition of apatite from the 1631 pyroclastics is different from those of CO2-rich melts indicating negligible CO2 content during magma evolution. Cross checking calculations, using PETROGRAPH and PELE software, accounts for multistage evolution up to phonolite starting from a phonolitic basanite melt similar to the Vesuvius medieval lavas. The model implies crystal settling of clinopyroxene and olivine at 6 kbar and 1220°C, clinopyroxene plus leucite at a pressure ranging from 2.5 to 0.5 kbar and temperature ranging from 1140 to 940°C. Inside the phonolitic magma chamber K-feldspar and leucite would coexist at a temperature ranging from from 940 to 840°C and at a pressure ranging from 2.5 to0.5 kbar. Thus crystal fractionation is certainly a necessary and probably a sufficient condition to evolve the melt from phono tephritic to phonolitic in the 1631 magma chamber. We speculate that phonolitic tephrite magma refilling from deeper levels destabilised the chamber and triggered the eruption, as testified by the seismic precursor phenomena before 1631 unrest.

  11. Advanced heat exchanger development for molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Sabharwall, Piyush, E-mail: Piyush.Sabharwall@inl.gov [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Clark, Denis; Glazoff, Michael [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark [University of Wisconsin, Madison (United States)

    2014-12-15

    Highlights: • Hastelloy N and 242, shows corrosion resistance to molten salt at nominal operating temperatures. • Both diffusion welds and sheet material in Hastelloy N were corrosion tested in at 650, 700, and 850 °C for 200, 500, and 1000 h. • Thermal gradients and galvanic couples in the molten salts enhance corrosion rates. • Corrosion rates found were typically <10 mils per year. - Abstract: This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non-nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, that show good corrosion resistance in molten salt at nominal operating temperatures up to 700 °C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in 58 mol% KF and 42 mol% ZrF{sub 4} at 650, 700, and 850 °C for 200, 500, and 1000 h. Corrosion rates were similar between welded and nonwelded materials, typically <100 μm per year after 1000 h of corrosion tests. No catastrophic corrosion was observed in the diffusion welded regions. For materials of construction, nickel-based alloys and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of the type of salt impurity and alloy composition, with respect to chromium and carbon, to better define the best conditions for corrosion resistance. Also presented is the division of the nuclear reactor and high-temperature components per American Society of Mechanical

  12. Intrusion of basaltic magma into a crystallizing granitic magma chamber: The Cordillera del Paine pluton in southern Chile

    Science.gov (United States)

    Michael, Peter J.

    1991-10-01

    The Cordillera del Paine pluton in the southernmost Andes of Chile represents a deeply dissected magma chamber where mafic magma intruded into crystallizing granitic magma. Throughout much of the 10x15 km pluton, there is a sharp and continuous boundary at a remarkably constant elevation of 1,100 m that separates granitic rocks (Cordillera del Paine or CP granite: 69 77% SiO2) which make up the upper levels of the pluton from mafic and comingled rocks (Paine Mafic Complex or PMC: 45 60% SiO2) which dominate the lower exposures of the pluton. Chilled, crenulate, disrupted contacts of mafic rock against granite demonstrate that partly crystallized granite was intruded by mafic magma which solidified prior to complete crystallization of the granitic magma. The boundary at 1,100 m was a large and stable density contrast between the denser, hotter mafic magma and cooler granitic magma. The granitic magma was more solidified near the margins of the chamber when mafic intrusion occurred, and the PMC is less disrupted by granites there. Near the pluton margins, the PMC grades upward irregularly from cumulate gabbros to monzodiorites. Mafic magma differentiated largely by fractional crystallization as indicated by the presence of cumulate rocks and by the low levels of compatible elements in most PMC rocks. The compositional gap between the PMC and CP granite indicates that mixing (blending) of granitic magma into the mafic magma was less important, although it is apparent from mineral assemblages in mafic rocks. Granitic magma may have incorporated small amounts of mafic liquid that had evolved to >60% SiO2 by crystallization. Mixing was inhibited by the extent of crystallization of the granite, and by the thermal contrast and the stable density contrast between the magmas. PMC gabbros display disequilibrium mineral assemblages including early formed zoned olivine (with orthopyroxene coronas), clinopyroxene, calcic plagioclase and paragasite and later-formed amphibole

  13. Dynamics of the Molten Contact Line

    Science.gov (United States)

    Sonin, Ain A.; Duthaler, Gregg; Liu, Michael; Torresola, Javier; Qiu, Taiqing

    1999-01-01

    The purpose of this program is to develop a basic understanding of how a molten material front spreads over a solid that is below its melting point, arrests, and freezes. Our hope is that the work will contribute toward a scientific knowledge base for certain new applications involving molten droplet deposition, including the "printing" of arbitrary three-dimensional objects by precise deposition of individual molten microdrops that solidify after impact. Little information is available at this time on the capillarity-driven motion and arrest of molten contact line regions. Schiaffino and Sonin investigated the arrest of the contact line of a molten microcrystalline wax spreading over a subcooled solid "target" of the same material. They found that contact line arrest takes place at an apparent liquid contact angle that depends primarily on the Stefan number S=c(T(sub f) -T(sub t)/L based on the temperature difference between the fusion point and the target temperature, and proposed that contact line arrest occurs when the liquid's dynamic contact angle approaches the angle of attack of the solidification front just behind the contact line. They also showed, however, that the conventional continuum equations and boundary conditions have no meaningful solution for this angle. The solidification front angle is determined by the heat flux just behind the contact line, and the heat flux is singular at that point. By comparing experiments with numerical computations, Schiaffino and Sonin estimated that the conventional solidification model must break down within a distance of order 0.1 - 1 microns of the contact line. The physical mechanism for this breakdown is as yet undetermined, and no first-principles theory exists for the contact angle at arrest. Schiaffino and Sonin also presented a framework for understanding how to moderate Weber number molten droplet deposition in terms of similarity laws and experimentation. The study is based on experiments with three molten

  14. Discovering Mathematics with Magma Reducing the Abstract to the Concrete

    CERN Document Server

    Bosma, Wieb

    2006-01-01

    With a design based on the ontology and semantics of algebra, Magma enables users to rapidly formulate and perform calculations in the more abstract parts of mathematics. This book introduces the role Magma plays in advanced mathematical research through 14 case studies which, in most cases, describe computations underpinning theoretical results.

  15. Zircons reveal magma fluxes in the Earth's crust.

    Science.gov (United States)

    Caricchi, Luca; Simpson, Guy; Schaltegger, Urs

    2014-07-24

    Magma fluxes regulate the planetary thermal budget, the growth of continents and the frequency and magnitude of volcanic eruptions, and play a part in the genesis and size of magmatic ore deposits. However, because a large fraction of the magma produced on the Earth does not erupt at the surface, determinations of magma fluxes are rare and this compromises our ability to establish a link between global heat transfer and large-scale geological processes. Here we show that age distributions of zircons, a mineral often present in crustal magmatic rocks, in combination with thermal modelling, provide an accurate means of retrieving magma fluxes. The characteristics of zircon age populations vary significantly and systematically as a function of the flux and total volume of magma accumulated in the Earth's crust. Our approach produces results that are consistent with independent determinations of magma fluxes and volumes of magmatic systems. Analysis of existing age population data sets using our method suggests that porphyry-type deposits, plutons and large eruptions each require magma input over different timescales at different characteristic average fluxes. We anticipate that more extensive and complete magma flux data sets will serve to clarify the control that the global heat flux exerts on the frequency of geological events such as volcanic eruptions, and to determine the main factors controlling the distribution of resources on our planet.

  16. Mixing of zeolite powders and molten salt

    International Nuclear Information System (INIS)

    Pereira, C.; Zyryanov, V.N.; Lewis, M.A.; Ackerman, J.P.

    1996-01-01

    Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic disposal. Both processes require mixing of zeolite powders with molten salt at elevated temperatures (>700 K). Complete occlusion of salt and a uniform distribution of chloride and fission products are desired for incorporation of the powders into the final waste form. The relative effectiveness of the blending process was studied over a series of temperature, time, and composition profiles. The major criteria for determining the effectiveness of the mixing operations were the level and uniformity of residual free salt in the mixtures. High operating temperatures (>775 K) improved salt occlusion. Reducing the chloride levels in the mixture to below 80% of the full salt capacity of the zeolite significantly reduced the free salt level in the final product

  17. Molten-salt reactor information system

    International Nuclear Information System (INIS)

    Haubenreich, P.N.; Cardwell, D.W.; Engel, J.R.

    1975-06-01

    The Molten-Salt Reactor Information System (MSRIS) is a computer-based file of abstracts of documents dealing with the technology of molten-salt reactors. The file is stored in the IBM-360 system at ORNL, and may be searched through the use of established interactive computer programs from remote terminals connected to the computer via telephone lines. The system currently contains 373 entries and is subject to updating and expansion as additional information is developed. The nature and general content of the data file, a general approach for obtaining information from it, and the manner in which material is added to the file are described. Appendixes provide the list of keywords currently in use, the subject categories under which information is filed, and simplified procedures for searching the file from remote terminals. (U.S.)

  18. Molten salt combustion of radioactive wastes

    International Nuclear Information System (INIS)

    Grantham, L.F.; McKenzie, D.E.; Richards, W.L.; Oldenkamp, R.D.

    1976-01-01

    The Atomics International Molten Salt Combustion Process reduces the weight and volume of combustible β-γ contaminated transuranic waste by utilizing air in a molten salt medium to combust organic materials, to trap particulates, and to react chemically with any acidic gases produced during combustion. Typically, incomplete combustion products such as hydrocarbons and carbon monoxide are below detection limits (i.e., 3 ) is directly related to the sodium chloride vapor pressure of the melt; >80% of the particulate is sodium chloride. Essentially all metal oxides (combustion ash) are retained in the melt, e.g., >99.9% of the plutonium, >99.6% of the europium, and >99.9% of the ruthenium are retained in the melt. Both bench-scale radioactive and pilot scale (50 kg/hr) nonradioactive combustion tests have been completed with essentially the same results. Design of three combustors for industrial applications are underway

  19. Pressure Dependence of Komatiite Liquid Viscosity and Implications for Magma Ocean Rheology

    Science.gov (United States)

    O'Dwyer Brown, L.; Lesher, C. E.; Terasaki, H. G.; Yamada, A.; Sakamaki, T.; Shibazaki, Y.; Ohtani, E.

    2009-12-01

    The viscosities of komatiite liquids at high pressures and temperatures were investigated using the in-situ falling sphere technique at BL04B1, SPring-8. Komatiites are naturally occurring magmas, rich in network modifying cations. Despite the refractory and fluid nature of komatiite, we successfully measured the viscosity of molten komatiites from Gorgona Island, Colombia (MgO = 17.8 wt.%; NBO/T = 1.5) between 11 and 13 GPa at 2000 C, and from Belingwe, Zimbabwe (MgO = 28.14 wt.%; NBO/T = 2.1) from 12 to 14 GPa at 2000 C. Under isothermal conditions, the viscosity of Gorgona Island komatiite melt increased with pressure, consistent with our previous measurements at lower pressures for this composition. We interpreted this positive pressure dependence as the result of reductions in interatomic space diminishing the free volume of the liquid when compressed. The viscosity of molten komatiite from Belingwe also increased up to 12 GPa, however between 12 and 14 GPa the viscosity is nearly constant. In previous studies of depolymerized silicate liquids, the pressure dependence of viscosity has been shown to reverse from positive to negative between 8 and 10 GPa with corresponding changes in activation volume [1] [2]. In contrast, the activation volume for Belingwe liquid decreases to near zero, but does not become negative above 11 GPa. Similarly, the activation volume for Gorgona Island komatiite remains positive throughout the pressure range investigated. Molecular dynamics simulations of simple MgO-SiO2 liquids with NBO/T > 2 also show a positive pressure dependence, reflecting the dominant control of free-volume reduction on the viscosity of depolymerized melts. However, the more rapid reduction in activation volume with pressure in komatiite liquids may be related to the presence of Al, Ti and other cations that interact and undergo coordination changes unavailable in simple silicate liquids. Along Hadean and post-Hadean mantle adiabats the net effect of

  20. Analysis of a molten salt reactor benchmark

    International Nuclear Information System (INIS)

    Ghosh, Biplab; Bajpai, Anil; Degweker, S.B.

    2013-01-01

    This paper discusses results of our studies of an IAEA molten salt reactor (MSR) benchmark. The benchmark, proposed by Japan, involves burnup calculations of a single lattice cell of a MSR for burning plutonium and other minor actinides. We have analyzed this cell with in-house developed burnup codes BURNTRAN and McBURN. This paper also presents a comparison of the results of our codes and those obtained by the proposers of the benchmark. (author)

  1. Molten salt battery having inorganic paper separator

    Science.gov (United States)

    Walker, Jr., Robert D.

    1977-01-01

    A high temperature secondary battery comprises an anode containing lithium, a cathode containing a chalcogen or chalcogenide, a molten salt electrolyte containing lithium ions, and a separator comprising a porous sheet comprising a homogenous mixture of 2-20 wt.% chrysotile asbestos fibers and the remainder inorganic material non-reactive with the battery components. The non-reactive material is present as fibers, powder, or a fiber-powder mixture.

  2. Electrochemical studies in molten sodium fluoroborate

    International Nuclear Information System (INIS)

    Brigaudeau, M.; Wagner, J.F.

    1979-01-01

    Physical properties of sodium fluoroborate are recalled and first results obtained during experimental study of molten NaBF 4 are exposed. The system Cu/CuF is used as an indicator of fluoride ion activity and dissociation constant of the solvent is determined by adding NaF to NaBF 4 saturated with BF 3 at a pressure of 1 atm and found equal to 2.7x10 -3 [fr

  3. Corrosion of technical ceramics by molten aluminium

    NARCIS (Netherlands)

    Schwabe, U.; Wolff, L.R.; Loo, van F.J.J.; Ziegler, G.

    1992-01-01

    The corrosion of 8 types of ceramics, i.e., 1 grade of hot isostatically pressed reaction-bonded Si3N4 (HIPRBSN), 3 grades of hot pressed Si3N4 (HPSN), and 4 grades of RBSN, and 2 types of SiC (HIPSiC and Si-impregnated SiC (SiSiC)) in molten Al (pure Al and AlZnMgCu1.5) was studied. The HIPRBSN and

  4. Partial oxidation process

    International Nuclear Information System (INIS)

    Najjar, M.S.

    1987-01-01

    A process is described for the production of gaseous mixtures comprising H/sub 2/+CO by the partial oxidation of a fuel feedstock comprising a heavy liquid hydrocarbonaceous fuel having a nickel, iron, and vanadium-containing ash or petroleum coke having a nickel, iron, and vanadium-containing ash, or mixtures thereof. The feedstock includes a minimum of 0.5 wt. % of sulfur and the ash includes a minimum of 5.0 wt. % vanadium, a minimum of 0.5 ppm nickel, and a minimum of 0.5 ppm iron. The process comprises: (1) mixing together a copper-containing additive with the fuel feedstock; wherein the weight ratio of copper-containing additive to ash in the fuel feedstock is in the range of about 1.0-10.0, and there is at least 10 parts by weight of copper for each part by weight of vanadium; (2) reacting the mixture from (1) at a temperature in the range of 2200 0 F to 2900 0 F and a pressure in the range of about 5 to 250 atmospheres in a free-flow refactory lined partial oxidation reaction zone with a free-oxygen containing gas in the presence of a temperature moderator and in a reducing atmosphere to produce a hot raw effluent gas stream comprising H/sub 2/+CO and entrained molten slag; and where in the reaction zone and the copper-containing additive combines with at least a portion of the nickel and iron constituents and sulfur found in the feedstock to produce a liquid phase washing agent that collects and transports at least a portion of the vanadium-containing oxide laths and spinels and other ash components and refractory out of the reaction zone; and (3) separating nongaseous materials from the hot raw effluent gas stream

  5. Emergence of two types of terrestrial planet on solidification of magma ocean.

    Science.gov (United States)

    Hamano, Keiko; Abe, Yutaka; Genda, Hidenori

    2013-05-30

    Understanding the origins of the diversity in terrestrial planets is a fundamental goal in Earth and planetary sciences. In the Solar System, Venus has a similar size and bulk composition to those of Earth, but it lacks water. Because a richer variety of exoplanets is expected to be discovered, prediction of their atmospheres and surface environments requires a general framework for planetary evolution. Here we show that terrestrial planets can be divided into two distinct types on the basis of their evolutionary history during solidification from the initially hot molten state expected from the standard formation model. Even if, apart from their orbits, they were identical just after formation, the solidified planets can have different characteristics. A type I planet, which is formed beyond a certain critical distance from the host star, solidifies within several million years. If the planet acquires water during formation, most of this water is retained and forms the earliest oceans. In contrast, on a type II planet, which is formed inside the critical distance, a magma ocean can be sustained for longer, even with a larger initial amount of water. Its duration could be as long as 100 million years if the planet is formed together with a mass of water comparable to the total inventory of the modern Earth. Hydrodynamic escape desiccates type II planets during the slow solidification process. Although Earth is categorized as type I, it is not clear which type Venus is because its orbital distance is close to the critical distance. However, because the dryness of the surface and mantle predicted for type II planets is consistent with the characteristics of Venus, it may be representative of type II planets. Also, future observations may have a chance to detect not only terrestrial exoplanets covered with water ocean but also those covered with magma ocean around a young star.

  6. Thorium molten-salt nuclear energy synergetics

    International Nuclear Information System (INIS)

    Furukawa, Kazuo

    1989-01-01

    One of the most practical and rational approaches for establishing the idealistic Thorium resource utilization program has been presented, which might be effective to solve the principal energy problems, concerning safety, proliferation and terrorism, resource, power size and fuel cycle economy, for the next century. The first step will be the development of Small Molten-Salt Reactors as a flexible power station, which is suitable for early commercialization of Th reactors not necessarily competing with proven Large Solid-Fuel Reactors. Therefore, the more detailed design works and practical R and D planning should be performed under the international cooperations soon, soundly depending on the basic technology established by ORNL already. R and D cost would be surprisingly low. This reactor(MSR) seems to be idealistic not only in power-size, siting, safety, safeguard and economy, but also as an effective partner of Molten-Salt Fissile Breeders(MSB) in order to establish the simplest and economical Thorium molten-salt breeding fuel cycle named THORIMS-NES in all over the world including the developing countries and isolated areas. This would be one of the most practical replies to the Lilienthal's appeal of 'A NEW START' in Nuclear Energy. (author)

  7. Thermal Characterization of Molten Salt Systems

    Energy Technology Data Exchange (ETDEWEB)

    Toni Y. Gutknecht; Guy L. Fredrickson

    2011-09-01

    The phase stability of molten salts in an electrorefiner (ER) may be adversely affected by the buildup of sodium, fission products, and transuranics in the electrolyte. Potential situations that need to be avoided are the following: (1) salt freezing due to an unexpected change in the liquidus temperature, (2) phase separation or non-homogeneity of the molten salt due to the precipitation of solids or formation of immiscible liquids, and (3) any mechanism that can result in the separation and concentration of fissile elements from the molten salt. Any of these situations would result in an off-normal condition outside the established safety basis for electrorefiner (ER) operations. The stability (and homogeneity) of the phases can potentially be monitored through the thermal characterization of the salts, which can be a function of impurity concentration. This report describes the experimental results of typical salts compositions, which consist of chlorides of potassium, lithium, strontium, samarium, praseodymium, lanthanum, barium, cerium, cesium, neodymium, sodium and gadolinium chlorides as a surrogate for both uranium and plutonium, used for the processing of used nuclear fuels.

  8. Thermal interaction of molten copper with water

    International Nuclear Information System (INIS)

    Zyszkowski, W.

    1975-01-01

    Experimental work was performed to study the thermal interaction between molten copper particles (in the range of temperature from the copper melting point to about 1800 0 C) and water from about 15-80 0 C. The transient temperatures of the copper particles and water before and during their thermal interaction were measured. The history of the phenomena was filmed by means of a high speed FASTAX camera (to 8000 f/s). Classification of the observed phenomena and description of the heat-transfer modes were derived. One among the phenomena was the thermal explosion. The necessary conditions for the thermal explosion are discussed and their physical interpretation is given. According to the hypothesis proposed, the thermal explosion occurs when the molten metal has the temperature of its solidification and the heat transfer on its surface is sufficiently intensive. The 'sharp-change' of the crystalline structure during the solidification of the molten metal is the cause of the explosion fragmentation. (author)

  9. Zircon crytallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    Science.gov (United States)

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Miff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ??? 60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction). ?? 2007 Geological Society of America.

  10. Zircon crystallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    Science.gov (United States)

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Tuff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ~60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction).

  11. Characteristics and Significance of Magma Emplacement Horizons, Black Sturgeon Sill, Nipigon, Ontario

    Science.gov (United States)

    Zieg, M. J.; Hone, S. V.

    2017-12-01

    Spatial scales strongly control the timescales of processes in igneous intrusions, particularly through the thermal evolution of the magma, which in turn governs the evolution of crystallinity, viscosity, and other important physical and chemical properties of the system. In this study, we have collected a highly detailed data set comprising geochemical (bulk rock composition), textural (size and alignment of plagioclase crystals), and mineralogical (modal abundance) profiles through the central portion of the 250 m thick Black Sturgeon diabase sill. In this data, we have identified characteristic signals in texture (soft and somewhat diffuse chills), composition (reversals in differentiation trends), and mineralogy (olivine accumulations), all coinciding and recurring at roughly 10 meter intervals. Based on these signatures, we are able to map out multiple zones representing discrete pulses of magma that were emplaced sequentially as the intrusion was inflated. Simple thermal calculations suggest that each 10 meters of new crystallization would require repose times on the order of 10-100 years. To build up 250 meters of magma at this rate would only require approximately 250-2500 years, significantly less than the thermal lifetime of the entire sill. The soft chills we observe in the Black Sturgeon sill are therefore consistent with a system that remained warm throughout the emplacement process. Successive pulses were injected into partially crystalline mush, rather than pure liquid (which would result in hybridization) or solid (which would produce sharp hard chills). Episodic emplacement is by now widely recognized as a fundamental process in the formation of large felsic magma chambers; our results suggest that this also may be an important consideration in understanding the evolution of smaller mafic intrusions.

  12. U-series isotopes in arc magma

    Energy Technology Data Exchange (ETDEWEB)

    Hawkesworth, C.; Turner, S.; McDermott, F.; Peate, D.; Van Calsteren, P.

    1997-12-31

    Thorium is not readily mobilized in the fluid component along destructive plate margins. Uranium is mobilized, and the resultant fractionation in U/Th can be used to estimate the rates of transfer slab derived components through the mantle wedge. The variations in Th/Yb, and by implication in the fractionation-corrected Th abundances of arc magmas largely depend on the contributions from subducted sediments. It is inferred that the distinctive high Th/Ta ratios of subduction related magmas primarily reflect the Th/Ta ratios of the subducted sediments, and that such high Th/Ta ratios are generated by processes other than those associated with recent subduction-related magmatism. Uranium and thorium isotopes have also been used to evaluate magma residence times within the crust. Thus, separated minerals and groundmass from six rocks erupted in the last 4,000 years from Soufriere on St. Vincent in the Lesser Antilles, scatter about a 50,000 year errorchron on the U-Th equiline diagram (Heath et al., 1977). Models are currently being developed to investigate how such apparent ages may relate to calculated replenishment times in steady state systems. Bulk continental crust has a lower U/Th ratio (0.25) than at least some estimates for the bulk Earth (0.26) and the depleted upper mantle (0.39). However, the island arc rocks with low U/Th ratios appear to have inherited those from subducted sediments, and arc rocks with a low sediment contribution have significantly higher U/Th. Consequently, the U/Th ratios of new crustal material generated along destructive plate margins are significantly higher than those of bulk continental crust. The low average U/Th of bulk crust may be primarily due to different crust generation processes in the Archaean, when U would be less mobile because conditions were less oxidising, and when residual garnet may have had more of a role in crust generation processes. Extended abstract. 4 figs., 23 refs.

  13. Magma heating by decompression-driven crystallization beneath andesite volcanoes.

    Science.gov (United States)

    Blundy, Jon; Cashman, Kathy; Humphreys, Madeleine

    2006-09-07

    Explosive volcanic eruptions are driven by exsolution of H2O-rich vapour from silicic magma. Eruption dynamics involve a complex interplay between nucleation and growth of vapour bubbles and crystallization, generating highly nonlinear variation in the physical properties of magma as it ascends beneath a volcano. This makes explosive volcanism difficult to model and, ultimately, to predict. A key unknown is the temperature variation in magma rising through the sub-volcanic system, as it loses gas and crystallizes en route. Thermodynamic modelling of magma that degasses, but does not crystallize, indicates that both cooling and heating are possible. Hitherto it has not been possible to evaluate such alternatives because of the difficulty of tracking temperature variations in moving magma several kilometres below the surface. Here we extend recent work on glassy melt inclusions trapped in plagioclase crystals to develop a method for tracking pressure-temperature-crystallinity paths in magma beneath two active andesite volcanoes. We use dissolved H2O in melt inclusions to constrain the pressure of H2O at the time an inclusion became sealed, incompatible trace element concentrations to calculate the corresponding magma crystallinity and plagioclase-melt geothermometry to determine the temperature. These data are allied to ilmenite-magnetite geothermometry to show that the temperature of ascending magma increases by up to 100 degrees C, owing to the release of latent heat of crystallization. This heating can account for several common textural features of andesitic magmas, which might otherwise be erroneously attributed to pre-eruptive magma mixing.

  14. The Experiences and Challenges in Drilling into Semi molten or Molten Intrusive in Menengai Geothermal Field

    Science.gov (United States)

    Mortensen, A. K.; Mibei, G. K.

    2017-12-01

    Drilling in Menengai has experienced various challenges related to drilling operations and the resource itself i.e. quality discharge fluids vis a vis gas content. The main reason for these challenges is related to the nature of rocks encountered at depths. Intrusives encountered within Menengai geothermal field have been group into three based on their geological characteristics i.e. S1, S2 and S3.Detailed geology and mineralogical characterization have not been done on these intrusive types. However, based on physical appearances, S1 is considered as a diorite dike, S2 is syenite while S3 is molten rock material. This paper summarizes the experiences in drilling into semi molten or molten intrusive (S3).

  15. Proposals on the organization of a fuel cycle of the cascade sub-critical molten salt reactor (CSMSR)

    International Nuclear Information System (INIS)

    Bychkov, A.V.; Kormilitsyn, M.V.; Melnik, M.I.; Babikov, L.G.; Ponomarev, L.I.

    2002-01-01

    At present the approach of burning out long-lived radioactive waste (RW) in the reactor core neutron flux is the most feasible one. Currently the way of closing nuclear fuel cycle (NFC) on the basis of the nuclear chemical concept of the cascade sub-critical molten salt reactor (CSMSR) is considered as the most promising one. It is characterised by a number of advantages. CSMSR controlled by a beam of protons or electrons is the optimal reactor for closing the NFC using non-aqueous fluoride methods of fuel reprocessing. They, in comparison with aqueous methods, are characterised by a small waste quantity and are less laborious because of the absence of severe requirements to the product purity. A high productivity of high-temperature electrochemical processes allows the implementation of the fuel recycling process as part of the CSMSR total technological cycle. It can be conducted in the 'on-line' mode in the bypass molten salt circuit that brings the transportation volume of high-activity materials to a minimum. In order to reprocess the CSMSR irradiated molten salt fuel on the basis of salt composition LiF-NaF-(BeF 2 ) an option, based on the following three main operations of the melt treatment, was proposed at SSC RF RIAR: (i) On-line argon treatment of molten salt fuel for removal of gaseous fission products (FP) and also FP that form volatile fluorides and aerosols; (ii) Organisation of the fuel-active metal (probably with a fine-dispersed plutonium alloy) interaction in the on-line mode for removal of 'noble' and 'semi-noble' FP and corrosion products such as Ni, Fe, Cr (when using Pu alloy it allows to regenerate at the same time of the burned-out plutonium component); (iii) Portion-by-portion (fuel composition partially being removed from the CSMSR molten salt circuit) pyroelectrochemical reprocessing of the molten salt composition aimed at the removal of lanthanides - FP followed by a return of actinides to the CSMSR fuel cycle. This technology will allow

  16. Molten salt engineering for thorium cycle. Electrochemical studies as examples

    International Nuclear Information System (INIS)

    Ito, Yasuhiko

    1998-01-01

    A Th-U nuclear energy system utilizing accelerator driven subcritical molten salt breeder reactor has several advantages compared to conventional U-Pu nuclear system. In order to obtain fundamental data on molten salt engineering of Th-U system, electrochemical study was conducted. As the most primitive simulated study of beam irradiation of molten salt, discharge electrolysis was investigated in molten LiCl-KCl-AgCl system. Stationary discharge was generated under atmospheric argon gas and fine Ag particles were obtained. Hydride ion (H - ) behavior in molten salts was also studied to predict the behavior of tritide ion (T - ) in molten salt fuel. Finally, hydrogen behavior in metals at high temperature was investigated by electrochemical method, which is considered to be important to confine and control tritium. (author)

  17. Tritium loss in molten flibe systems

    Energy Technology Data Exchange (ETDEWEB)

    Longhurst, G.R.; Anderl, R.A. [Idaho National Eng. and Environ. Lab., Idaho Falls, ID (United States); Scott Willms, R. [Los Alamos National Lab., NM (United States)

    2000-04-01

    An emerging issue relative to beryllium technology in fusion involves tritium interactions with molten beryllium-bearing salts. Innovative designs for fusion reactors, both magnetic and inertially confined, feature the molten salt mixture 2LiF.BeF{sub 2}, commonly called Flibe, as a tritium breeder and coolant. Tritium is bred in the Flibe as neutrons from the plasma are absorbed by Li atoms, which then transmute to tritium and helium. Transmutation of tritium from Be also occurs. Among the issues to be resolved for such coolant systems is the potential loss of tritium from the Flibe coolant to the walls of the system, particularly through heat exchanger tubes, and from there into secondary coolants or working fluids and the environment. Effectively removing tritium from Flibe in clean-up units is also important. In quiescent or low Reynolds number flow, tritium movement through Flibe is governed by diffusion. For Flibe in turbulent flow, as in heat exchanger tubes, transport is by turbulent mixing, and the same flow conditions and structural design features that maximize heat transfer to the heat exchanger walls will enhance the transport of tritium to those same surfaces. Analyses have been performed to estimate the fractional loss of tritium through heat exchanger tubes and release rates from Flibe droplets in vacuum disengagers in molten Flibe systems. The calculations suggest unacceptably large losses of tritium through heat exchanger tubes. The gravity of the implications of these estimates calls for experimental verification to determine if tritium losses through molten Flibe heat exchangers or other Flibe systems can really be so high and whether vacuum disengagers will really work. There is also a need for better information on evolution of tritium from Flibe droplets in a vacuum. Several experiments are presently being planned to address these issues and are discussed. These include experiments to induce tritium in Flibe using spontaneous fission neutrons

  18. Tritium loss in molten flibe systems

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Anderl, R.A.; Scott Willms, R.

    2000-01-01

    An emerging issue relative to beryllium technology in fusion involves tritium interactions with molten beryllium-bearing salts. Innovative designs for fusion reactors, both magnetic and inertially confined, feature the molten salt mixture 2LiF.BeF 2 , commonly called Flibe, as a tritium breeder and coolant. Tritium is bred in the Flibe as neutrons from the plasma are absorbed by Li atoms, which then transmute to tritium and helium. Transmutation of tritium from Be also occurs. Among the issues to be resolved for such coolant systems is the potential loss of tritium from the Flibe coolant to the walls of the system, particularly through heat exchanger tubes, and from there into secondary coolants or working fluids and the environment. Effectively removing tritium from Flibe in clean-up units is also important. In quiescent or low Reynolds number flow, tritium movement through Flibe is governed by diffusion. For Flibe in turbulent flow, as in heat exchanger tubes, transport is by turbulent mixing, and the same flow conditions and structural design features that maximize heat transfer to the heat exchanger walls will enhance the transport of tritium to those same surfaces. Analyses have been performed to estimate the fractional loss of tritium through heat exchanger tubes and release rates from Flibe droplets in vacuum disengagers in molten Flibe systems. The calculations suggest unacceptably large losses of tritium through heat exchanger tubes. The gravity of the implications of these estimates calls for experimental verification to determine if tritium losses through molten Flibe heat exchangers or other Flibe systems can really be so high and whether vacuum disengagers will really work. There is also a need for better information on evolution of tritium from Flibe droplets in a vacuum. Several experiments are presently being planned to address these issues and are discussed. These include experiments to induce tritium in Flibe using spontaneous fission neutrons

  19. Longevity of magma in the near subsurface

    International Nuclear Information System (INIS)

    Marsh, B.D.; Resmini, R.G.

    1992-01-01

    Small, sporadic occurrences of basaltic volcanism are particularly difficult to evaluate in terms of long term threat to mankind because of their short overall eruptive history. Insight into future eruptive vigor and possible subsurface magma storage may be furnished by studying the ages of crystals in the eruptive products themselves. In this paper, the authors do this by applying the method of crystal size distribution theory (CSD) to a stack of basaltic lavas within the Nevada test site; namely the Dome Mtn. lavas. Preliminary results suggest a pre-eruptive residence time of 10 - 20 years, decreasing with decreasing age of lava within the sequence. These times are similar to those found by M.T. Mangan for the 1959 Kilauea (Hawaii) eruptions, and may suggest a relatively vigorous magmatic system at this time some 8 m.y. ago. Work is progressing on a greatly expanded CSD analysis of the Dome Mtn. lavas

  20. Permeability During Magma Expansion and Compaction

    Science.gov (United States)

    Gonnermann, Helge. M.; Giachetti, Thomas; Fliedner, Céline; Nguyen, Chinh T.; Houghton, Bruce F.; Crozier, Joshua A.; Carey, Rebecca J.

    2017-12-01

    Plinian lapilli from the 1060 Common Era Glass Mountain rhyolitic eruption of Medicine Lake Volcano, California, were collected and analyzed for vesicularity and permeability. A subset of the samples were deformed at a temperature of 975°, under shear and normal stress, and postdeformation porosities and permeabilities were measured. Almost all undeformed samples fall within a narrow range of vesicularity (0.7-0.9), encompassing permeabilities between approximately 10-15 m2 and 10-10 m2. A percolation threshold of approximately 0.7 is required to fit the data by a power law, whereas a percolation threshold of approximately 0.5 is estimated by fitting connected and total vesicularity using percolation modeling. The Glass Mountain samples completely overlap with a range of explosively erupted silicic samples, and it remains unclear whether the erupting magmas became permeable at porosities of approximately 0.7 or at lower values. Sample deformation resulted in compaction and vesicle connectivity either increased or decreased. At small strains permeability of some samples increased, but at higher strains permeability decreased. Samples remain permeable down to vesicularities of less than 0.2, consistent with a potential hysteresis in permeability-porosity between expansion (vesiculation) and compaction (outgassing). We attribute this to retention of vesicle interconnectivity, albeit at reduced vesicle size, as well as bubble coalescence during shear deformation. We provide an equation that approximates the change in permeability during compaction. Based on a comparison with data from effusively erupted silicic samples, we propose that this equation can be used to model the change in permeability during compaction of effusively erupting magmas.

  1. Variations in magma supply rate at Kilauea Volcano, Hawaii

    Science.gov (United States)

    Dvorak, John J.; Dzurisin, Daniel

    1993-01-01

    When an eruption of Kilauea lasts more than 4 months, so that a well-defined conduit has time to develop, magma moves freely through the volcano from a deep source to the eruptive site at a constant rate of 0.09 km3/yr. At other times, the magma supply rate to Kilauea, estimated from geodetic measurements of surface displacements, may be different. For example, after a large withdrawal of magma from the summit reservoir, such as during a rift zone eruption, the magma supply rate is high initially but then lessens and exponentially decays as the reservoir refills. Different episodes of refilling may have different average rates of magma supply. During four year-long episodes in the 1960s, the annual rate of refilling varied from 0.02 to 0.18 km3/yr, bracketing the sustained eruptive rate of 0.09 km3/yr. For decade-long or longer periods, our estimate of magma supply rate is based on long-term changes in eruptive rate. We use eruptive rate because after a few dozen eruptions the volume of magma that passes through the summit reservoir is much larger than the net change of volume of magma stored within Kilauea. The low eruptive rate of 0.009 km3/yr between 1840 and 1950, compared to an average eruptive rate of 0.05 km3/yr since 1950, suggests that the magma supply rate was lower between 1840 and 1950 than it has been since 1950. An obvious difference in activity before and since 1950 was the frequency of rift zone eruptions: eight rift zone eruptions occurred between 1840 and 1950, but more than 20 rift zone eruptions have occurred since 1950. The frequency of rift zone eruptions influences magma supply rate by suddenly lowering pressure of the summit magma reservoir, which feeds magma to rift zone eruptions. A temporary drop of reservoir pressure means a larger-than-normal pressure difference between the reservoir and a deeper source, so magma is forced to move upward into Kilauea at a faster rate.

  2. Molten metal feed system controlled with a traveling magnetic field

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1991-01-01

    This patent describes a continuous metal casting system in which the feed of molten metal controlled by means of a linear induction motor capable of producing a magnetic traveling wave in a duct that connects a reservoir of molten metal to a caster. The linear induction motor produces a traveling magnetic wave in the duct in opposition to the pressure exerted by the head of molten metal in the reservoir

  3. Compatibility studies of potential molten-salt breeder reactor materials in molten fluoride salts

    International Nuclear Information System (INIS)

    Keiser, J.R.

    1977-05-01

    The molten fluoride salt compatibility studies carried out during the period 1974--76 in support of the Molten-Salt Reactor Program are summarized. Thermal-convection and forced-circulation loops were used to measure the corrosion rate of selected alloys. Results confirmed the relationship of time, initial chromium concentration, and mass loss developed by previous workers. The corrosion rates of Hastelloy N and Hastelloy N modified by the addition of 1--3 wt percent Nb were well within the acceptable range for use in an MSBR. 13 figures, 3 tables

  4. Accelerator molten-salt breeding and thorium fuel cycle

    International Nuclear Information System (INIS)

    Furukawa, Kazuo; Nakahara, Yasuaki; Kato, Yoshio; Ohno, Hideo; Mitachi, Kohshi.

    1990-01-01

    The recent efforts at the development of fission energy utilization have not been successful in establishing fully rational technology. A new philosophy should be established on the basis of the following three principles: (1) thorium utilization, (2) molten-salt fuel concept, and (3) separation of fissile-breeding and power-generating functions. Such philosophy is called 'Thorium Molten-Salt Nuclear Energy Synergetics [THORIMS-NES]'. The present report first addresses the establishment of 233 U breeding fuel cycle, focusing on major features of the Breeding and Chemical Processing Centers and a small molten-salt power station (called FUJI-II). The development of fissile producing breeders is discussed in relation to accelerator molten-salt breeder (AMSB), impact fusion molten-salt breeder, and inertial-confined fusion hybrid molten-salt breeder. Features of the accelerator molten-salt breeder are described, focusing on technical problems with accelerator breeders (or spallators), design principle of the accelerator molten-salt breeder, selection of molten salt compositions, and nuclear- and reactor-chemical aspects of AMSB. Discussion is also made of further research and development efforts required in the future for AMSB. (N.K.)

  5. Crust formation and its effect on the molten pool coolability

    Energy Technology Data Exchange (ETDEWEB)

    Park, R.J.; Lee, S.J.; Sim, S.K. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-09-01

    Experimental and analytical studies of the crust formation and its effect on the molten pool coolability have been performed to examine the crust formation process as a function of boundary temperatures as well as to investigate heat transfer characteristics between molten pool and overlying water in order to evaluate coolability of the molten pool. The experimental test results have shown that the surface temperature of the bottom plate is a dominant parameter in the crust formation process of the molten pool. It is also found that the crust thickness of the case with direct coolant injection into the molten pool is greater than that of the case with a heat exchanger. Increasing mass flow rate of direct coolant injection to the molten pool does not affect the temperature of molten pool after the crust has been formed in the molten pool because the crust behaves as a thermal barrier. The Nusselt number between the molten pool and the coolant of the case with no crust formation is greater than that of the case with crust formation. The results of FLOW-3D analyses have shown that the temperature distribution contributes to the crust formation process due to Rayleigh-Benard natural convection flow.

  6. Core-concrete molten pool dynamics and interfacial heat transfer

    International Nuclear Information System (INIS)

    Benjamin, A.S.

    1980-01-01

    Theoretical models are derived for the heat transfer from molten oxide pools to an underlying concrete surface and from molten steel pools to a general concrete containment. To accomplish this, two separate effects models are first developed, one emphasizing the vigorous agitation of the molten pool by gases evolving from the concrete and the other considering the insulating effect of a slag layer produced by concrete melting. The resulting algebraic expressions, combined into a general core-concrete heat transfer representation, are shown to provide very good agreement with experiments involving molten steel pours into concrete crucibles

  7. Studies on components for a molten salt reactor

    International Nuclear Information System (INIS)

    Nejedly, M.; Matal, O.

    2003-01-01

    The aim is contribute to a design of selected components of molten salt reactors with fuel in the molten fluoride salt matrix. Molten salt reactors (MSRs) permit the utilization of plutonium and minor actinides as new nuclear fuel from a traditional nuclear power station with production of electric energy. Results of preliminary feasibility studies of an intermediate heat exchanger, a small power molten salt pump and a modular conception of a steam generator for a demonstration unit of the MSR (30 MW) are summarized. (author)

  8. MAGMA: analysis of two-channel microarrays made easy.

    Science.gov (United States)

    Rehrauer, Hubert; Zoller, Stefan; Schlapbach, Ralph

    2007-07-01

    The web application MAGMA provides a simple and intuitive interface to identify differentially expressed genes from two-channel microarray data. While the underlying algorithms are not superior to those of similar web applications, MAGMA is particularly user friendly and can be used without prior training. The user interface guides the novice user through the most typical microarray analysis workflow consisting of data upload, annotation, normalization and statistical analysis. It automatically generates R-scripts that document MAGMA's entire data processing steps, thereby allowing the user to regenerate all results in his local R installation. The implementation of MAGMA follows the model-view-controller design pattern that strictly separates the R-based statistical data processing, the web-representation and the application logic. This modular design makes the application flexible and easily extendible by experts in one of the fields: statistical microarray analysis, web design or software development. State-of-the-art Java Server Faces technology was used to generate the web interface and to perform user input processing. MAGMA's object-oriented modular framework makes it easily extendible and applicable to other fields and demonstrates that modern Java technology is also suitable for rather small and concise academic projects. MAGMA is freely available at www.magma-fgcz.uzh.ch.

  9. Forecasting magma-chamber rupture at Santorini volcano, Greece.

    Science.gov (United States)

    Browning, John; Drymoni, Kyriaki; Gudmundsson, Agust

    2015-10-28

    How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily cause an eruption but produces a net volume change that can be measured geodetically by inversion techniques. Using continuum-mechanics and fracture-mechanics principles, we calculate the amount of magma contained at shallow depth beneath Santorini volcano, Greece. We demonstrate through structural analysis of dykes exposed within the Santorini caldera, previously published data on the volume of recent eruptions, and geodetic measurements of the 2011-2012 unrest period, that the measured 0.02% increase in volume of Santorini's shallow magma chamber was associated with magmatic excess pressure increase of around 1.1 MPa. This excess pressure was high enough to bring the chamber roof close to rupture and dyke injection. For volcanoes with known typical extrusion and intrusion (dyke) volumes, the new methodology presented here makes it possible to forecast the conditions for magma-chamber failure and dyke injection at any geodetically well-monitored volcano.

  10. Partial Cancellation

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Partial Cancellation. Full Cancellation is desirable. But complexity requirements are enormous. 4000 tones, 100 Users billions of flops !!! Main Idea: Challenge: To determine which cross-talker to cancel on what “tone” for a given victim. Constraint: Total complexity is ...

  11. Study on electrolytic reduction with controlled oxygen flow for iron from molten oxide slag containing FeO

    Directory of Open Access Journals (Sweden)

    Gao Y.M.

    2013-01-01

    Full Text Available A ZrO2-based solid membrane electrolytic cell with controlled oxygen flow was constructed: graphite rod /[O]Fe+C saturated / ZrO2(MgO/(FeO slag/iron crucible. The feasibility of extraction of iron from molten oxide slag containing FeO at an applied voltage was investigated by means of the electrolytic cell. The effects of some important process factors on the FeO electrolytic reduction with the controlled oxygen flow were discussed. The results show that: solid iron can be extracted from molten oxide slag containing FeO at 1450ºC and an applied potential of 4V. These factors, such as precipitation and growth of solid iron dendrites, change of the cathode active area on the inner wall of the iron crucible and ion diffusion flux in the molten slag may affect the electrochemical reaction rate. The reduction for Fe2+ ions mainly appears on new iron dendrites of the iron crucible cathode, and a very small amount of iron are also formed on the MSZ (2.18% MgO partially stabilized zirconia tube/slag interface due to electronic conductance of MSZ tube. Internal electronic current through MSZ tube may change direction at earlier and later electrolytic reduction stage. It has a role of promoting electrolytic reduction for FeO in the molten slag at the earlier stage, but will lower the current efficiency at the later stage. The final reduction ratio of FeO in the molten slag can achieve 99%. A novel electrolytic method with controlled oxygen flow for iron from the molten oxide slag containing FeO was proposed. The theory of electrolytic reduction with the controlled oxygen flow was developed.

  12. Magma paths at Piton de la Fournaise Volcano

    OpenAIRE

    Michon , Laurent; Ferrazzini , Valérie; Di Muro , Andrea

    2016-01-01

    International audience; Several patterns of magma paths have been proposed since the 1980s for Piton de la Fournaise volcano. Given the significant differences, which are presented here, we propose a reappraisal of the magma intrusion paths using a 17-years-long database of volcano-tectonic seismic events and a detailed mapping of the scoria cones. At the edifice scale, the magma propagates along two N120 trending rift zones. They are wide, linear, spotted by small to large scoria cones and r...

  13. Magma Expansion and Fragmentation in a Propagating Dike (Invited)

    Science.gov (United States)

    Jaupart, C. P.; Taisne, B.

    2010-12-01

    The influence of magma expansion due to volatile exsolution and gas dilation on dike propagation is studied using a new numerical code. Many natural magmas contain sufficient amounts of volatiles for fragmentation to occur well below Earth's surface. Magma fragmentation has been studied for volcanic flows through open conduits but it should also occur within dikes that rise towards Earth's surface. We consider the flow of a volatile-rich magma in a hydraulic fracture. The mixture of melt and gas is treated as a compressible viscous fluid below the fragmentation level and as a gas phase carrying melt droplets above it. A numerical code solves for elastic deformation of host rocks, the flow of the magmatic mixture and fracturing at the dike tip. With volatile-free magma, a dike fed at a constant rate in a uniform medium adopts a constant shape and width and rises at a constant velocity. With volatiles involved, magma expands and hence the volume flux of magma increases. With no fragmentation, this enhanced flux leads to acceleration of the dike. Simple scaling laws allow accurate predictions of dike width and ascent rate for a wide range of conditions. With fragmentation, dike behavior is markedly different. Due to the sharp drop of head loss that occurs in gas-rich fragmented material, large internal overpressures develop below the tip and induce swelling of the nose region, leading to deceleration of the dike. Thus, the paradoxical result is that, with no viscous impediment on magma flow and a large buoyancy force, the dike stalls. This process may account for some of the tuffisite veins and intrusions that are found in and around magma conduits, notably in the Unzen drillhole, Japan. We apply these results to the two-month long period of volcanic unrest that preceded the May 1980 eruption of Mount St Helens. An initial phase of rapid earthquake migration from the 7-8 km deep reservoir to shallow levels was followed by very slow progression of magma within the

  14. Short-circuiting magma differentiation from basalt straight to rhyolite?

    Science.gov (United States)

    Ruprecht, P.; Winslow, H.

    2017-12-01

    Silicic magmas are the product of varying degrees of crystal fractionation and crustal assimilation/melting. Both processes lead to differentiation that is step-wise rather than continuous for example during melt separation from a crystal mush (Dufek and Bachmann, 2010). However, differentiation is rarely efficient enough to evolve directly from a basaltic to a rhyolitic magma. At Volcán Puyehue-Cordón Caulle, Chile, the magma series is dominated by crystal fractionation where mixing trends between primitive and felsic end members in the bulk rock compositions are almost absent (e.g. P, FeO, TiO2 vs. SiO2). How effective fraction is in this magmatic system is not well-known. The 2011-12 eruption at Cordón Caulle provides new constraints that rhyolitic melts may be derived directly from a basaltic mush. Minor, but ubiquitous mafic, crystal-rich enclaves co-erupted with the predominantly rhyolitic near-aphyric magma. These enclaves are among the most primitive compositions erupted at Puyehue-Cordón Caulle and geochemically resemble closely basaltic magmas that are >10 ka old (Singer et al. 2008) and that have been identified as a parental tholeiitic mantle-derived magma (Schmidt and Jagoutz, 2017) for the Southern Andean Volcanic Zone. The vesiculated nature, the presence of a microlite-rich groundmass, and a lack of a Eu anomaly in these encalves suggest that they represent recharge magma/mush rather than sub-solidus cumulates and therefore have potentially a direct petrogenetic link to the erupted rhyolites. Our results indicate that under some conditions crystal fractionation can be very effective and the presence of rhyolitic magmas does not require an extensive polybaric plumbing system. Instead, primitive mantle-derived magmas source directly evolved magmas. In the case, of the magma system beneath Puyehue-Cordón Caulle, which had three historic rhyolitic eruptions (1921-22, 1960, 2011-12) these results raise the question whether rhyolite magma extraction

  15. Genesis of felsic plutonic magmas and their igneous enclaves

    DEFF Research Database (Denmark)

    Clemens, John D.; Maas, Roland; Waight, Tod Earle

    2016-01-01

    -type Pyalong pluton was emplaced, apparently along an east-west-orientated fracture zone. Around 367 Ma, the main I-type Baynton pluton intruded as numerous shallow-dipping sheets. The last plutonic event was the intrusion of the broad, thin, flat-lying, and crosscutting sheet of the I-type Beauvallet pluton...... the relatively high abundance of igneous-textured microgranular enclaves (MEs). The MEs show neither chemical nor isotope mixing trends with each other or with the host magmas. Variations in the Baynton magmas were derived from the heterogeneity of the source terrane, with individual magma batches formed from...

  16. Heat and Fission Product Transport in a Molten U-Zr-O Pool With Crust

    International Nuclear Information System (INIS)

    Yun, J.I.; Suh, K.Y.; Kang, C.S.

    2002-01-01

    Heat transfer and fluid flow in a molten pool are influenced by internal volumetric heat generated from the radioactive decay of fission product species retained in the pool. The pool superheat is determined based on the overall energy balance that equates the heat production rate to the heat loss rate. Decay heat of fission products in the pool was estimated by product of the mass concentration and energy conversion factor of each fission product. For the calculation of heat generation rate in the pool, twenty-nine elements were chosen and classified by their chemical properties. The mass concentration of a fission product is obtained from released fraction and the tabular output of the ORIGEN 2 code. The initial core and pool inventories at each time can also be estimated using ORIGEN 2. The released fraction of each fission product is calculated based on the bubble dynamics and mass transport. Numerical analysis was performed for the TMI-2 accident. The pool is assumed to be a partially filled hemispherical geometry and the change of pool geometry during the numerical calculation was neglected. Results of the numerical calculation revealed that the peak temperature of the molten pool significantly decreased and most of the volatile fission products were released from the molten pool during the accident. (authors)

  17. Effect of Degassing Treatment on the Interfacial Reaction of Molten Aluminum and Solid Steel

    Directory of Open Access Journals (Sweden)

    Triyono T.

    2017-06-01

    Full Text Available The gas porosity is one of the most serious problems in the casting of aluminum. There are several degassing methods that have been studied. During smelting of aluminum, the intermetallic compound (IMC may be formed at the interface between molten aluminum and solid steel of crucible furnace lining. In this study, the effect of degassing treatment on the formations of IMC has been investigated. The rectangular substrate specimens were immersed in a molten aluminum bath. The holding times of the substrate immersions were in the range from 300 s to 1500 s. Two degassing treatments, argon degassing and hexachloroethane tablet degassing, were conducted to investigate their effect on the IMC formation. The IMC was examined under scanning electron microscope with EDX attachment. The thickness of the IMC layer increased with increasing immersion time for all treatments. Due to the high content of hydrogen, substrate specimens immersed in molten aluminum without degasser had IMC layer which was thicker than others. Argon degassing treatment was more effective than tablet degassing to reduce the IMC growth. Furthermore, the hard and brittle phase of IMC, FeAl3, was formed dominantly in specimens immersed for 900 s without degasser while in argon and tablet degasser specimens, it was formed partially.

  18. Thorium-based Molten Salt Reactor (TMSR) project in China

    International Nuclear Information System (INIS)

    Dai, Zhimin; Liu, Wei

    2013-01-01

    Making great efforts in development of nuclear energy is one of the long-term-plan in China's energy strategies. The advantages of Thorium-based nuclear energy are: rich resource in nature, less nuclear waste, low toxicity, nuclear non-proliferation and so on. Furthermore, China is a country with abundant thorium, thus it is necessary to develop the Thorium-based Molten Salt Reactor (TMSR) in China. Shanghai Institute of Applied Physics, Chinese Academy of Sciences (SINAP) had designed and constructed the first China's light-water reactor and developed a zero-power thorium-based molten salt reactor successfully in the early 1970s. The applied research project 'thorium molten salt reactor nuclear power system' by SINAP together with several other institutes had been accepted and granted by China government in 2011. The whole project has been divided into three stages: Firstly, built a 2 MW-zero-power high temperature solid molten salt reactor in 2015 and a 2 MW-zero-power high temperature liquid molten salt reactor in 2017. Secondly, in 2020 built a 10 MW high temperature liquid molten salt reactor. Thirdly, on the base of previous work, a 100 MW high temperature molten salt reactor should be achieving in 2030. After more than one years of efforts, a high quality scientific research team has been formed, which is able to design the molten salt reactor, the molten salt loop and related key equipment, the systems of molten salt preparation, purification and the radioactive gas removal. In the past one year, the initial physical design of high temperature molten salt reactor has been completed; the nuclear chemistry and radiation chemical laboratory has been built, a high temperature salt (HTS) loop and radioactive gas removal experiment device system have been successfully developed and constructed. Further, the preliminary study on reactor used carbon-carbon composite material has been investigated. (author)

  19. Electrochemical studies on plutonium in molten salts

    International Nuclear Information System (INIS)

    Bourges, G.; Lambertin, D.; Rochefort, S.; Delpech, S.; Picard, G.

    2007-01-01

    Electrochemical studies on plutonium have been supporting the development of pyrochemical processes involving plutonium at CEA. The electrochemical properties of plutonium have been studied in molten salts - ternary eutectic mixture NaCl-KCl-BaCl 2 , equimolar mixture NaCl-KCl and pure CaCl 2 - and in liquid gallium at 1073 K. The formal, or apparent, standard potential of Pu(III)/Pu redox couple in eutectic mixture of NaCl-KCl-BaCl 2 at 1073 K determined by potentiometry is equal to -2.56 V (versus Cl 2 , 1 atm/Cl - reference electrode). In NaCl-KCl eutectic mixture and in pure CaCl 2 the formal standard potentials deduced from cyclic voltammetry are respectively -2.54 V and -2.51 V. These potentials led to the calculation of the activity coefficients of Pu(III) in the molten salts. Chronoamperometry on plutonium in liquid gallium using molten chlorides - CaCl 2 and equimolar NaCl/KCl - led to the determination of the activity coefficient of Pu in liquid Ga, log γ = -7.3. This new data is a key parameter to assess the thermodynamic feasibility of a process using gallium as solvent metal. By comparing gallium with other solvent metals - cadmium, bismuth, aluminum - gallium appears to be, with aluminum, more favorable for the selectivity of the separation at 1073 K of plutonium from cerium. In fact, compared with a solid tungsten electrode, none of these solvent liquid metals is a real asset for the selectivity of the separation. The role of a solvent liquid metal is mainly to trap the elements

  20. Partial processing

    International Nuclear Information System (INIS)

    1978-11-01

    This discussion paper considers the possibility of applying to the recycle of plutonium in thermal reactors a particular method of partial processing based on the PUREX process but named CIVEX to emphasise the differences. The CIVEX process is based primarily on the retention of short-lived fission products. The paper suggests: (1) the recycle of fission products with uranium and plutonium in thermal reactor fuel would be technically feasible; (2) it would, however, take ten years or more to develop the CIVEX process to the point where it could be launched on a commercial scale; (3) since the majority of spent fuel to be reprocessed this century will have been in storage for ten years or more, the recycling of short-lived fission products with the U-Pu would not provide an effective means of making refabrication fuel ''inaccessible'' because the radioactivity associated with the fission products would have decayed. There would therefore be no advantage in partial processing

  1. Applications of molten salts in plutonium processing

    International Nuclear Information System (INIS)

    Bowersox, D.F.; Christensen, D.C.; Williams, J.D.

    1987-01-01

    Plutonium is efficiently recovered from scrap at Los Alamos by a series of chemical reactions and separations conducted at temperatures ranging from 700 to 900 0 C. These processes usually employ a molten salt or salt eutectic as a heat sink and/or reaction medium. Salts for these operations were selected early in the development cycle. The selection criteria are being reevaluated. In this article we describe the processes now in use at Los Alamos and our studies of alternate salts and eutectics

  2. Apparatus for controlling molten core debris

    International Nuclear Information System (INIS)

    Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

    1972-01-01

    Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures

  3. Electrorecovery of tantalum in molten fluorides

    International Nuclear Information System (INIS)

    Espinola, A.; Dutra, A.J.B.; Silva, F.T. da

    1988-01-01

    Considering the privileged situation of Brazil as a productor of tantaliferous minerals, the authors have in view the development of a technology for production of metallic tantalum via molten salts electrolysis; this has the advantage of improving the aggregate value of exportation products, additionally to tantalum oxide and tantalum concentrates. Having in view the preliminary determintion of better conditions of temperature, electrolyte composition and current density for this process, electrolysis were conducted with a solvent composed of an eutetic mixture of lithium, sodium and potassium fluoride for dipotassium fluotantalate and occasionally for tantalum oxide. Current efficiencies as high as 83% were obtained in favoured conditions. (author) [pt

  4. Safe actinide disposition in molten salt reactors

    International Nuclear Information System (INIS)

    Gat, U.

    1997-01-01

    Safe molten salt reactors (MSR) can readily accommodate the burning of all fissile actinides. Only minor compromises associated with plutonium are required. The MSRs can dispose safely of actinides and long lived isotopes to result in safer and simpler waste. Disposing of actinides in MSRs does increase the source term of a safety optimized MSR. It is concluded that the burning and transmutation of actinides in MSRs can be done in a safe manner. Development is needed for the processing to handle and separate the actinides. Calculations are needed to establish the neutron economy and the fuel management. 9 refs

  5. Partial gigantism

    Directory of Open Access Journals (Sweden)

    М.М. Karimova

    2017-05-01

    Full Text Available A girl with partial gigantism (the increased I and II fingers of the left foot is being examined. This condition is a rare and unresolved problem, as the definite reason of its development is not determined. Wait-and-see strategy is recommended, as well as correcting operations after closing of growth zones, and forming of data pool for generalization and development of schemes of drug and radial therapeutic methods.

  6. Heat and fission product transport in molten core material pool with crust

    International Nuclear Information System (INIS)

    Yun, J.I.; Suh, K.Y.; Kang, C.S.

    2005-01-01

    Heat transfer and fluid flow in a molten pool are influenced by internal volumetric heat generated from the radioactive decay of fission product species retained in the reactor vessel during a severe accident. The pool superheat is determined based on the overall energy balance that equates the heat production rate to the heat loss rate. Decay heat of fission products in the pool is estimated by product of the mass concentration and energy conversion factor of each fission product. Twenty-nine elements are chosen and classified by their chemical properties to calculate heat generation rate in the pool. The mass concentration of a fission product is obtained from released fraction and the tabular output of the ORIGEN 2 code. The initial core and pool inventories at each time can also be estimated using ORIGEN 2. The released fraction of each fission product is calculated based on the bubble dynamics and mass transport. Numerical analysis is performed for heat and fission product transport in a molten core material pool during the Three Mile Island Unit 2 (TMI-2) accident. The pool is assumed to be a partially filled hemisphere, whose change in geometry is neglected during the numerical calculation. Calculated results indicate that the peak temperature in the molten pool is significantly lowered, since a substantial amount of the volatile fission products is released from the molten pool during progression of the accident. The results may directly be applied to the existing severe accident analysis codes to more mechanistically determine the thermal load to the reactor vessel lower head during the in-vessel retention

  7. Water Partitioning in Planetary Embryos and Protoplanets with Magma Oceans

    Science.gov (United States)

    Ikoma, M.; Elkins-Tanton, L.; Hamano, K.; Suckale, J.

    2018-06-01

    The water content of magma oceans is widely accepted as a key factor that determines whether a terrestrial planet is habitable. Water ocean mass is determined as a result not only of water delivery and loss, but also of water partitioning among several reservoirs. Here we review our current understanding of water partitioning among the atmosphere, magma ocean, and solid mantle of accreting planetary embryos and protoplanets just after giant collisions. Magma oceans are readily formed in planetary embryos and protoplanets in their accretion phase. Significant amounts of water are partitioned into magma oceans, provided the planetary building blocks are water-rich enough. Particularly important but still quite uncertain issues are how much water the planetary building blocks contain initially and how water goes out of the solidifying mantle and is finally degassed to the atmosphere. Constraints from both solar-system explorations and exoplanet observations and also from laboratory experiments are needed to resolve these issues.

  8. Understanding the rheology of two and three-phase magmas

    Science.gov (United States)

    Coats, R.; Cai, B.; Kendrick, J. E.; Wallace, P. A.; Hornby, A. J.; Miwa, T.; von Aulock, F. W.; Ashworth, J. D.; Godinho, J.; Atwood, R. C.; Lee, P. D.; Lavallée, Y.

    2017-12-01

    The rheology of magma plays a fundamental role in determining the style of a volcanic eruption, be it explosive or effusive. Understanding how magmas respond to changes in stress/ strain conditions may help to enhance eruption forecast models. The presence of crystals and bubbles in magmas alter the viscosity of suspensions and favor a non-Newtonian response. Thus, with the aim of grasping the rheological behavior of volcanic materials, uniaxial compressive tests were performed on natural and synthetic samples. A suite of variably porous (10-32 vol.%), highly crystalline ( 50 vol.%) dacite from the 1991-95 eruption of Mt Unzen, Japan, was selected as the natural material, while synthetic samples were sintered with desired porosities (Diamond Light Source. Unexpectedly, these observations suggest that fractures nucleate in crystals due to crystal interactions, before propagating through the interstitial melt. This ongoing study promises to uncover the way crystal-bearing magmas flow or fail, necessary to constrain magmatic processes and volcanic hazards.

  9. Implications of magma transfer between multiple reservoirs on eruption cycling.

    Science.gov (United States)

    Elsworth, Derek; Mattioli, Glen; Taron, Joshua; Voight, Barry; Herd, Richard

    2008-10-10

    Volcanic eruptions are episodic despite being supplied by melt at a nearly constant rate. We used histories of magma efflux and surface deformation to geodetically image magma transfer within the deep crustal plumbing of the Soufrière Hills volcano on Montserrat, West Indies. For three cycles of effusion followed by discrete pauses, supply of the system from the deep crust and mantle was continuous. During periods of reinitiated high surface efflux, magma rose quickly and synchronously from a deflating mid-crustal reservoir (at about 12 kilometers) augmented from depth. During repose, the lower reservoir refilled from the deep supply, with only minor discharge transiting the upper chamber to surface. These observations are consistent with a model involving the continuous supply of magma from the deep crust and mantle into a voluminous and compliant mid-crustal reservoir, episodically valved below a shallow reservoir (at about 6 kilometers).

  10. Production and Preservation of Sulfide Layering in Mercury's Magma Ocean

    Science.gov (United States)

    Boukare, C.-E.; Parman, S. W.; Parmentier, E. M.; Anzures, B. A.

    2018-05-01

    Mercury's magma ocean (MMO) would have been sulfur-rich. At some point during MMO solidification, it likely became sulfide saturated. Here we present physiochemical models exploring sulfide layer formation and stability.

  11. Magma chamber processes in central volcanic systems of Iceland

    DEFF Research Database (Denmark)

    Þórarinsson, Sigurjón Böðvar; Tegner, Christian

    2009-01-01

    are composed of 2-10 m thick melanocratic layers rich in clinopyroxene and sometimes olivine, relative to the thicker overlying leucocratic oxide gabbros. While the overall compositional variation is limited (Mg# clinopyroxene 72-84; An% plagioclase 56-85), the melanocratic bases display spikes in Mg# and Cr2O......3 of clinopyroxene and magnetite indicative of magma replenishment. Some macrorhythmic units show mineral trends indicative of up-section fractional crystallisation over up to 100 m, whereas others show little variation. Two populations of plagioclase crystals (large, An-rich and small, less An......-rich) indicate that the recharge magma carried plagioclase xenocrysts (high An-type). The lack of evolved gabbros suggests formation in a dynamic magma chamber with frequent recharge, tapping and fractionation. Modelling of these compositional trends shows that the parent magma was similar to known transitional...

  12. Interaction of calcium oxide with molten alkali metal chlorides

    International Nuclear Information System (INIS)

    Volkovich, A.V.; Zhuravlev, V.I.; Ermakov, D.S.; Magurina, M.V.

    1999-01-01

    Calcium oxide solubility in molten lithium, sodium, potassium, cesium chlorides and their binary mixtures is determined in a temperature range of 973-1173 K by the method of isothermal saturation. Mechanisms of calcium oxide interaction with molten alkali metal chlorides are proposed

  13. Molten salt fueled reactors with a fast salt draining

    International Nuclear Information System (INIS)

    Ventre, Edmond; Blum, J.M.

    1976-01-01

    This invention relates to a molten salt nuclear reactor which comprises a new arrangement for shutting it down in complete safety. This nuclear reactor has a molten salt primary circuit comprising, in particular, the core of this reactor. It includes a leak tight vessel the capacity of which is appreciably greater than that of the molten salt volume of the circuit and placed so that the level of the molten salt, when all the molten salt of the circuit is contained in this vessel, is less than that of the base of the core. There are facilities for establishing and maintaining an inert gas pressure in the vessel above the molten salt, for releasing the compressed gas and for connecting the vessel to the primary circuit entering this vessel at a lower level than that of the molten salt and enabling molten salt to enter or leave the vessel according to the pressure of the inert gas. The particular advantage of this reactor is that it can be shut down safely since the draining of the primary circuit no longer results from a 'positive action' but from the suppression of an arrangement essential for the operation of the reactor consisting of the build-up of the said inert gas pressure in the said vessel [fr

  14. Advancing Molten Salts and Fuels at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Salvador B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-26

    SNL has a combination of experimental facilities, nuclear engineering, nuclear security, severe nuclear accidents, and nuclear safeguards expertise that can enable significant progress towards molten salts and fuels for Molten Salt Reactors (MSRs). The following areas and opportunities are discussed in more detail in this white paper.

  15. On the ionic equilibrium between complexes in molten fluoroaluminates

    International Nuclear Information System (INIS)

    Akdeniz, Z.; Tankeshwar, K.; Tosi, M.P.

    1991-02-01

    We discuss theoretically (i) the effect of the alkali cation species on the ionic equilibrium between (AlF 6 ) 3- and (AlF 4 ) - complexes in molten alkali fluoroaluminates, and (ii) the possible presence of (AlF 5 ) 2 - complexes in molten cryolite, in relation to very recent Raman scattering experiments by Gilbert and Materne. (author). 7 refs, 2 tabs

  16. 46 CFR 151.50-55 - Sulfur (molten).

    Science.gov (United States)

    2010-10-01

    ... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-55 Sulfur (molten). (a.... Heat transfer media shall be steam, and alternate media will require specific approval of the... 46 Shipping 5 2010-10-01 2010-10-01 false Sulfur (molten). 151.50-55 Section 151.50-55 Shipping...

  17. Seismic Tremors and Three-Dimensional Magma Wagging

    Science.gov (United States)

    Liao, Y.; Bercovici, D.

    2015-12-01

    Seismic tremor is a feature shared by many silicic volcanoes and is a precursor of volcanic eruption. Many of the characteristics of tremors, including their frequency band from 0.5 Hz to 7 Hz, are common for volcanoes with very different geophysical and geochemical properties. The ubiquitous characteristics of tremor imply that it results from some generation mechanism that is common to all volcanoes, instead of being unique to each volcano. Here we present new analysis on the magma-wagging mechanism that has been proposed to generate tremor. The model is based on the suggestion given by previous work (Jellinek & Bercovici 2011; Bercovici et.al. 2013) that the magma column is surrounded by a compressible, bubble-rich foam annulus while rising inside the volcanic conduit, and that the lateral oscillation of the magma inside the annulus causes observable tremor. Unlike the previous two-dimensional wagging model where the displacement of the magma column is restricted to one vertical plane, the three-dimensional model we employ allows the magma column to bend in different directions and has angular motion as well. Our preliminary results show that, without damping from viscous deformation of the magma column, the system retains angular momentum and develops elliptical motion (i.e., the horizontal displacement traces an ellipse). In this ''inviscid'' limit, the magma column can also develop instabilities with higher frequencies than what is found in the original two-dimensional model. Lateral motion can also be out of phase for various depths in the magma column leading to a coiled wagging motion. For the viscous-magma model, we predict a similar damping rate for the uncoiled magma column as in the two-dimensional model, and faster damping for the coiled magma column. The higher damping thus requires the existence of a forcing mechanism to sustain the oscillation, for example the gas-driven Bernoulli effect proposed by Bercovici et al (2013). Finally, using our new 3

  18. Magma chamber interaction giving rise to asymmetric oscillations

    Science.gov (United States)

    Walwer, D.; Ghil, M.; Calais, E.

    2017-12-01

    Geodetic time series at four volcanoes (Okmok, Akutan, Shishaldin, and Réunion) are processed using Multi-channel Singular Spectrum Analysis (M-SSA) and reveal sawtooth-shaped oscillations ; the latter are characterized by short intervals of fast inflations followed by longer intervals of slower deflations. At Okmok and Akutan, the oscillations are first damped and then accentuated. At Okmok, the increase in amplitude of the oscillations is followed by an eruption. We first show that the dynamics of these four volcanoes bears similarities with that of a simple nonlinear, dissipative oscillator, indicating that the inflation-deflation episodes are relaxation oscillations. These observations imply that ab initio dynamical models of magma chambers should possess an asymmetric oscillatory regime. Next, based on the work of Whitehead and Helfrich [1991], we show that a model of two magma chambers — connected by a cylindrical conduit in which the magma viscosity depends on temperature — gives rise to asymmetric overpressure oscillations in the magma reservoirs. These oscillations lead to surface deformations that are consistent with those observed at the four volcanoes in this study. This relaxation oscillation regime occurs only when the vertical temperature gradient in the host rock between the two magma chambers is large enough and when the magma flux entering the volcanic system is sufficiently high. The magma being supplied by a deeper source region, the input flux depends on the pressure difference between the source and the deepest reservoir. When this difference is not sufficiently high, the magma flux exponentially decreases, leading to damped oscillations as observed at Akutan and Okmok. The combination of observational and modeling results clearly supports the role of relaxation oscillations in the dynamics of volcanic systems.

  19. Crystalline heterogeneities and instabilities in thermally convecting magma chamber

    Science.gov (United States)

    Culha, C.; Suckale, J.; Qin, Z.

    2016-12-01

    A volcanic vent can supply different densities of crystals over an eruption time period. This has been seen in Hawai'i's Kilauea Iki 1959 eruption; however it is not common for all Kilauea or basaltic eruptions. We ask the question: Under what conditions can homogenous magma chamber cultivate crystalline heterogeneities? In some laboratory experiments and numerical simulations, a horizontal variation is observed. The region where crystals reside is identified as a retention zone: convection velocity balances settling velocity. Simulations and experiments that observe retention zones assume crystals do not alter the convection in the fluid. However, a comparison of experiments and simulations of convecting magma with crystals suggest that large crystal volume densities and crystal sizes alter fluid flow considerably. We introduce a computational method that fully resolves the crystalline phase. To simulate basaltic magma chambers in thermal convection, we built a numerical solver of the Navier-Stoke's equation, continuity equation, and energy equation. The modeled magma is assumed to be a viscous, incompressible fluid with a liquid and solid phase. Crystals are spherical, rigid bodies. We create Rayleigh-Taylor instability through a cool top layer and hot bottom layer and update magma density while keeping crystal temperature and size constant. Our method provides a detailed picture of magma chambers, which we compare to other models and experiments to identify when and how crystals alter magma chamber convection. Alterations include stratification, differential settling and instabilities. These characteristics are dependent on viscosity, convection vigor, crystal volume density and crystal characteristics. We reveal that a volumetric crystal density variation may occur over an eruption time period, if right conditions are met to form stratifications and instabilities in magma chambers. These conditions are realistic for Kilauea Iki's 1959 eruption.

  20. Experimental Fractional Crystallization of the Lunar Magma Ocean

    Science.gov (United States)

    Rapp, J. F.; Draper, D. S.

    2012-01-01

    The current paradigm for lunar evolution is of crystallization of a global scale magma ocean, giving rise to the anorthositic crust and mafic cumulate interior. It is thought that all other lunar rocks have arisen from this differentiated interior. However, until recently this paradigm has remained untested experimentally. Presented here are the first experimental results of fractional crystallization of a Lunar Magma Ocean (LMO) using the Taylor Whole Moon (TWM) bulk lunar composition [1].

  1. Magma Dynamics at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    D. Krier

    2005-01-01

    Small-volume basaltic volcanic activity at Yucca Mountain has been identified as one of the potential events that could lead to release of radioactive material from the U.S. Department of Energy (DOE) designated nuclear waste repository at Yucca Mountain. Release of material could occur indirectly as a result of magmatic dike intrusion into the repository (with no associated surface eruption) by changing groundwater flow paths, or as a result of an eruption (dike intrusion of the repository drifts, followed by surface eruption of contaminated ash) or volcanic ejection of material onto the Earth's surface and the redistribution of contaminated volcanic tephra. Either release method includes interaction between emplacement drifts and a magmatic dike or conduit, and natural (geologic) processes that might interrupt or halt igneous activity. This analysis provides summary information on two approaches to evaluate effects of disruption at the repository by basaltic igneous activity: (1) descriptions of the physical geometry of ascending basaltic dikes and their interaction with silicic host rocks similar in composition to the repository host rocks; and (2) a summary of calculations developed to quantify the response of emplacement drifts that have been flooded with magma and repressurized following blockage of an eruptive conduit. The purpose of these analyses is to explore the potential consequences that could occur during the full duration of an igneous event

  2. Magma Dynamics at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    D. Krier

    2005-08-29

    Small-volume basaltic volcanic activity at Yucca Mountain has been identified as one of the potential events that could lead to release of radioactive material from the U.S. Department of Energy (DOE) designated nuclear waste repository at Yucca Mountain. Release of material could occur indirectly as a result of magmatic dike intrusion into the repository (with no associated surface eruption) by changing groundwater flow paths, or as a result of an eruption (dike intrusion of the repository drifts, followed by surface eruption of contaminated ash) or volcanic ejection of material onto the Earth's surface and the redistribution of contaminated volcanic tephra. Either release method includes interaction between emplacement drifts and a magmatic dike or conduit, and natural (geologic) processes that might interrupt or halt igneous activity. This analysis provides summary information on two approaches to evaluate effects of disruption at the repository by basaltic igneous activity: (1) descriptions of the physical geometry of ascending basaltic dikes and their interaction with silicic host rocks similar in composition to the repository host rocks; and (2) a summary of calculations developed to quantify the response of emplacement drifts that have been flooded with magma and repressurized following blockage of an eruptive conduit. The purpose of these analyses is to explore the potential consequences that could occur during the full duration of an igneous event.

  3. The fluid dynamics of a basaltic magma chamber replenished by influx of hot, dense ultrabasic magma

    Science.gov (United States)

    Huppert, Herbert E.; Sparks, R. Stephen J.

    1981-09-01

    This paper describes a fluid dynamical investigation of the influx of hot, dense ultrabasic magma into a reservoir containing lighter, fractionated basaltic magma. This situation is compared with that which develops when hot salty water is introduced under cold fresh water. Theoretical and empirical models for salt/water systems are adapted to develop a model for magmatic systems. A feature of the model is that the ultrabasic melt does not immediately mix with the basalt, but spreads out over the floor of the chamber, forming an independent layer. A non-turbulent interface forms between this layer and the overlying magma layer across which heat and mass are transferred by the process of molecular diffusion. Both layers convect vigorously as heat is transferred to the upper layer at a rate which greatly exceeds the heat lost to the surrounding country rock. The convection continues until the two layers have almost the same temperature. The compositions of the layers remain distinct due to the low diffusivity of mass compared to heat. The temperatures of the layers as functions of time and their cooling rate depend on their viscosities, their thermal properties, the density difference between the layers and their thicknesses. For a layer of ultrabasic melt (18% MgO) a few tens of metres thick at the base of a basaltic (10% MgO) magma chamber a few kilometres thick, the temperature of the layers will become nearly identical over a period of between a few months and a few years. During this time the turbulent convective velocities in the ultrabasic layer are far larger than the settling velocity of olivines which crystallise within the layer during cooling. Olivines only settle after the two layers have nearly reached thermal equilibrium. At this stage residual basaltic melt segregates as the olivines sediment in the lower layer. Depending on its density, the released basalt can either mix convectively with the overlying basalt layer, or can continue as a separate

  4. Experimental studies of oxidic molten corium-vessel steel interaction

    International Nuclear Information System (INIS)

    Bechta, S.V.; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V.

    2001-01-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere

  5. Experimental studies of oxidic molten corium-vessel steel interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V. E-mail: niti-npc@sbor.net; Khabensky, V.B.; Vitol, S.A.; Krushinov, E.V.; Lopukh, D.B.; Petrov, Yu.B.; Petchenkov, A.Yu.; Kulagin, I.V.; Granovsky, V.S.; Kovtunova, S.V.; Martinov, V.V.; Gusarov, V.V

    2001-12-01

    The experimental results of molten corium-steel specimen interaction with molten corium on the 'Rasplav-2' test facility are presented. In the experiments, cooled vessel steel specimens positioned on the molten pool bottom and uncooled ones lowered into the molten pool were tested. Interaction processes were studied for different corium compositions, melt superheating and in alternative (inert and air) overlying atmosphere. Hypotheses were put forward explaining the observed phenomena and interaction mechanisms. The studies presented in the paper were aimed at the detection of different corium-steel interaction mechanisms. Therefore certain identified phenomena are more typical of the ex-vessel localization conditions than of the in-vessel corium retention. Primarily, this can be referred to the phenomena of low-temperature molten corium-vessel steel interaction in oxidizing atmosphere.

  6. Measurement and analyses of molten Ni-Co alloy density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; K. MUKAI; FANG Liang; FU Ya; YANG Ren-hui

    2006-01-01

    With the advent of powerful mathematical modeling techniques for material phenomena, there is renewed interest in reliable data for the density of the Ni-based superalloys. Up to now, there has been few report on the density of molten Ni-Co alloy.In order to obtain more accurate density data for molten Ni-Co alloy, the density of molten Ni-Co alloy was measured with a modified sessile drop method, and the accommodation of different atoms in molten Ni-Co alloy was analyzed. The density of alloy is found to decrease with increasing temperature and Co concentration in the alloy. The molar volume of molten Ni-Co alloy increases with increasing Co concentration. The molar volume of Ni-Co alloy determined shows a positive deviation from the linear molar volume, and the deviation of molar volume from ideal mixing increases with increasing Co concentration over the experimental concentration range.

  7. Advances in molten salt electrochemistry towards future energy systems

    International Nuclear Information System (INIS)

    Ito, Yasuhiko

    2005-01-01

    This review article describes some selected novel molten salt electrochemical processes which have been created/developed by the author and his coworkers, with emphasis on the applications towards future energy systems. After showing a perspective of the applications of molten salt electrochemistry from the viewpoints of energy and environment, several selected topics are described in detail, which include nitride fuel cycle in a nuclear field, hydrogen energy system coupled with ammonia economy, thermally regenerative fuel cell systems, novel Si production process for solar cell and novel molten salt electrochemical processes for various energy and environment related functional materials including nitrides, rare earth-transition metal alloys, fine particles obtained by plasma-induced electrolysis, and carbon film. And finally, the author stresses again, the importance and potential of molten salt electrochemistry, and encourages young students, scientists and researchers to march in a procession hand in hand towards a bright future of molten salts. (author)

  8. Molten salt extractive distillation process for zirconium-hafnium separation

    International Nuclear Information System (INIS)

    McLaughlin, D.F.; Stoltz, R.A.

    1989-01-01

    This patent describes an improvement in a process for zirconium-hafnium separation. It utilizes an extractive distillation column with a mixture of zirconium and hafnium tetrachlorides introduced into a distillation column having a top and bottom with hafnium enriched overheads taken from the top of the column and a molten salt solvent circulated through the column to provide a liquid phase, and with molten salt solvent containing zirconium chloride being taken from the bottom of the distillation column. The improvements comprising: utilizing a molten salt solvent consisting principally of lithium chloride and at least one of sodium, potassium, magnesium and calcium chlorides; stripping of the zirconium chloride taken from the bottom of the distillation column by electrochemically reducing zirconium from the molten salt solvent; and utilizing a pressurized reflux condenser on the top of the column to add the hafnium chloride enriched overheads to the molten salt solvent previously stripped of zirconium chloride

  9. Molten core material holding device in a nuclear reactor

    International Nuclear Information System (INIS)

    Nakamura, Hisashi; Tanaka, Nobuo; Takahashi, Katsuro.

    1985-01-01

    Purpose: To improve the function of cooling to hold molten core materials in a molten core material holding device. Constitution: Plenum structures are formed into a pan-like configuration, in which liners made of metal having high melting point and relatively high heat conductivity such as tantalum, tungsten, rhenium or alloys thereof are integrally appended to hold and directly cool the molten reactor core materials. Further, a plurality of heat pipes, passing through the plenum structures, facing the cooling portion thereof to the coolants at the outer side and immersing the heating portion into the molten core materials fallen to deposit in the inner liners are disposed radially. Furthermore, heat pipes embodded in the plenum structure are disposed in the same manner below the liners. Thus, the plenum structures and the molten reactor core materials can be cooled at a high efficiency. (Seki, T.)

  10. Fuel processing for molten-salt reactors

    International Nuclear Information System (INIS)

    Hightower, J.R. Jr.

    1976-01-01

    Research devoted to development of processes for the isolation of protactinium and for the removal of fission products from molten-salt breeder reactors is reported. During this report period, engineering development progressed on continuous fluorinators for uranium removal, the metal transfer process for rare-earth removal, the fuel reconstitution step, and molten salt--bismuth contactors to be used in reductive extraction processes. The metal transfer experiment MTE-3B was started. In this experiment all parts of the metal transfer process for rare-earth removal are demonstrated using salt flow rates which are about 1 percent of those required to process the fuel salt in a 1000-MW(e) MSBR. During this report period the salt and bismuth phases were transferred to the experimental vessels, and two runs with agitator speeds of 5 rps were made to measure the rate of transfer of neodymium from the fluoride salt to the Bi--Li stripper solution. The uranium removed from the fuel salt by fluorination must be returned to the processed salt in the fuel reconstitution step before the fuel salt is returned to the reactor. An engineering experiment to demonstrate the fuel reconstitution step is being installed. In this experiment gold-lined equipment will be used to avoid introducing products of corrosion by UF 6 and UF 5 . Alternative methods for providing the gold lining include electroplating and mechanical fabrication

  11. Organic waste processing using molten salt oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, M. G., LLNL

    1998-03-01

    Molten Salt Oxidation (MSO) is a thermal means of oxidizing (destroying) the organic constituents of mixed wastes, hazardous wastes, and energetic materials while retaining inorganic and radioactive constituents in the salt. For this reason, MSO is considered a promising alternative to incineration for the treatment of a variety of organic wastes. The U. S. Department of Energy`s Office of Environmental Management (DOE/EM) is currently funding research that will identify alternatives to incineration for the treatment of organic-based mixed wastes. (Mixed wastes are defined as waste streams which have both hazardous and radioactive properties.) One such project is Lawrence Livermore National Laboratory`s Expedited Technology Demonstration of Molten Salt Oxidation (MSO). The goal of this project is to conduct an integrated demonstration of MSO, including off-gas and spent salt treatment, and the preparation of robust solid final forms. Livermore National Laboratory (LLNL) has constructed an integrated pilot-scale MSO treatment system in which tests and demonstrations are presently being performed under carefully controlled (experimental) conditions. The system consists of a MSO process vessel with dedicated off-gas treatment, a salt recycle system, feed preparation equipment, and equipment for preparing ceramic final waste forms. In this paper we describe the integrated system and discuss its capabilities as well as preliminary process demonstration data. A primary purpose of these demonstrations is to identify the most suitable waste streams and waste types for MSO treatment.

  12. The Relationship Between Carbonatitic, Melilititic and Potassic Trachytic Magma Types at the Saltpeterkop Carbonatite Complex, Sutherland, South Africa

    Science.gov (United States)

    Janney, P. E.; Marageni, M.

    2016-12-01

    The 74 Ma Saltpeterkop Carbonatite Complex near Sutherland, South Africa, is unusual in that it is one of the few southern African carbonatites with preserved volcanic features, including a 1 km-diameter tuff ring composed of silicified volcaniclastic breccia. Around the complex, the regionally flat-lying Karoo strata have been dramatically upwarped, with dips away from the Complex as high as 45°. Further, within about a 10 km radius of the center of the complex are hundreds of dikes, sills and diatremes composed mainly of carbonatite, potassic trachyte and olivine melilitite, with the spatial density of these intrusions decreasing with increasing distance. We have recently completed an in-depth geochemical reconnaissance of the Saltpeterkop complex, involving field sampling and whole-rock major and trace element analysis, with radiogenic and stable isotope measurements in progress. While the association with potassic trachytes is relatively common in southern African carbonatites, the presence of significant amounts of primitive olivine melilitite (30-40 wt.% SiO2, Mg# = 61-74) is unusual. Our preliminary model for the origin of the complex involves (1) ascent and intrusion of a mantle-derived carbonated and potassic magma into the mid-to upper crust, (2a) separation of an alkali carbonatite phase from this magma, resulting in intensive local fenitization and partial melting of mid-crustal rocks (thereby forming potassic trachytes), and possibly triggering the initial eruption, (2b) small amounts of primitive, but now less potassic, mantle-derived magma are emplaced as olivine melilitite dikes and diatremes, and (3) differentiation of the mantle-derived magma to generate significant quantities of mainly calcio- and ferro-carbonatite magmas emplaced as dykes and sills.

  13. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  14. Re-appraisal of the Magma-rich versus Magma-poor Paradigm at Rifted Margins: consequences for breakup processes

    Science.gov (United States)

    Tugend, J.; Gillard, M.; Manatschal, G.; Nirrengarten, M.; Harkin, C. J.; Epin, M. E.; Sauter, D.; Autin, J.; Kusznir, N. J.; McDermott, K.

    2017-12-01

    Rifted margins are often classified based on their magmatic budget only. Magma-rich margins are commonly considered to have excess decompression melting at lithospheric breakup compared with steady state seafloor spreading while magma-poor margins have suppressed melting. New observations derived from high quality geophysical data sets and drill-hole data have revealed the diversity of rifted margin architecture and variable distribution of magmatism. Recent studies suggest, however, that rifted margins have more complex and polyphase tectono-magmatic evolutions than previously assumed and cannot be characterized based on the observed volume of magma alone. We compare the magmatic budget related to lithospheric breakup along two high-resolution long-offset deep reflection seismic profiles across the SE-Indian (magma-poor) and Uruguayan (magma-rich) rifted margins. Resolving the volume of magmatic additions is difficult. Interpretations are non-unique and several of them appear plausible for each case involving variable magmatic volumes and mechanisms to achieve lithospheric breakup. A supposedly 'magma-poor' rifted margin (SE-India) may show a 'magma-rich' lithospheric breakup whereas a 'magma-rich' rifted margin (Uruguay) does not necessarily show excess magmatism at lithospheric breakup compared with steady-state seafloor spreading. This questions the paradigm that rifted margins can be subdivided in either magma-poor or magma-rich margins. The Uruguayan and other magma-rich rifted margins appear characterized by an early onset of decompression melting relative to crustal breakup. For the converse, where the onset of decompression melting is late compared with the timing of crustal breakup, mantle exhumation can occur (e.g. SE-India). Our work highlights the difficulty in determining a magmatic budget at rifted margins based on seismic reflection data alone, showing the limitations of margin classification based solely on magmatic volumes. The timing of

  15. Understanding the mechanical coupling between magma emplacement and the resulting deformation: the example of saucer-shaped sills

    Science.gov (United States)

    Galland, O.; Neumann, E. R.; Planke, S.

    2009-12-01

    The mechanical coupling between magma intrusions and the surrounding rocks plays a major role in the emplacement of volcanic plumbing systems. The deformation associated with magma emplacement has been widely studied, such as caldera inflation/deflation, volcano deformation during dike intrusion, and doming above laccoliths. However, the feedback processes, i.e. the effect of deformation resulting from intruding magma on the propagation of the intrusion itself, have rarely been studied. Saucer-shaped sills are adequate geological objects to understand such processes. Indeed, observation show that saucer-shaped sills are often associated with dome-like structures affecting the overlying sediments. In addition, there is a clear geometrical relation between the sills and the domes: the dome diameters are almost identical to those of saucers, and the tips of the inclined sheets of saucers are superimposed on the edges of the domes. In this presentation, we report on experimental investigations of the emplacement mechanisms of saucer-shaped sills and associated deformation. The model materials were (1) cohesive fine-grained silica flour, representing brittle crust, and (2) molten low-viscosity oil, representing magma. A weak layer located at the top of the injection inlet simulates strata. The main variable parameter is injection depth. During experiments, the surface of the model is digitalized through a structured light technique based on the moiré projection principle. Such a tool provides topographic maps of the surface of the model and allows a periodic (every 1.5 s) monitoring of the model topography. When the model magma starts intruding, a symmetrical dome rises above the inlet. Subsequently, the dome inflates and widens, and then evolves to a plateau-like feature, with nearly flat upper surface and steep sides. At the end of the experiments, the intruding liquid erupts at the edge of the plateau. The intrusions formed in the experiments are saucer-shaped sills

  16. Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle

    Science.gov (United States)

    Bacon, C.R.; Bruggman, P.E.; Christiansen, R.L.; Clynne, M.A.; Donnelly-Nolan, J. M.; Hildreth, W.

    1997-01-01

    ; and OIB-source-like domains. Lavas with arc and intraplate (OIB) geochemical signatures were erupted close to HAOT, and many lavas are blends of two or more magma types. Pre-eruptive H2O contents of HAOT, coupled with phase-equilibrium studies, suggest that these magmas were relatively dry and last equilibrated in the mantle wedge at temperatures of ???1300??C and depths of ???40 km, virtually at the base of the crust. Arc basalt and basaltic andesite represent greater extents of melting than HAOT, presumably in the same general thermal regime but at somewhat lower mantle separation temperatures, of domains of sub-arc mantle that have been enriched by a hydrous subduction component derived from the young, relatively hot Juan de Fuca plate. The primitive magmas originated by partial melting in response to adiabatic upwelling within the mantle wedge. Tectonic extension in this part of the Cascade arc, one characterized by slow oblique convergence, contributes to mantle upwelling and facilitates eruption of primitive magmas.

  17. Preliminary Results on a Contact between 4 kg of Molten UO2 and Liquid Sodium

    International Nuclear Information System (INIS)

    Amblard, M.

    1976-01-01

    The CORECT II Experiment consists in simulating the penetration of sodium into an assembly when the fuel is molten. In other words, it is a shock-tube type of experiment with dimensions representative of a full-scale assembly. the experiment consists in dropping a 100 litre column of sodium onto partially molten UO 2 . The following measurements are carried out in transient regime: - sodium velocity in the column; - pressure in the interaction chamber; - pressures at the bottom and at the top of a 5 m tube; - pressure in the argon blanket. The experimental parameters are: - the mass of UO 2 involved (about 4 or 7 kg of 80% molten UO 2 ); - the initial temperature of the sodium (up to 700 deg. C); - the pressure of the residual gas in the interaction chamber during the fall of the sodium; - the dimensions of the interaction chamber and the sodium supply tube; - the form of contact between the UO 2 and the sodium (the sodium may fall on partially liquid and settled UO 2 or on UO 2 pre-dispersed by forced trapping of sodium). To date, 6 tests have been performed. These tests have always resulted in fine fragmentation without any violent interaction. Since no knowledge is available on the change of grain size distribution with time, on the temperature of grain formation, and on the grain movement in the sodium, it is very difficult to interpret these UO 2 -Na tests. We intend to carry out more severe interaction tests on this experimental set-up, by eliminating as much as possible the non-condensable gas which cushions the mechanical impact of the sodium on the UO 2 (tests have shown that by strongly de-pressurizing the liquid UO 2 the fuel could be dispersed by boiling, and this effect should also improve the possibilities of a liquid/liquid contact). - by injecting a little sodium into the UO 2 to facilitate its dispersion in the coolant

  18. Fast molten salt reactor-transmuter for closing nuclear fuel cycle on minor actinides

    International Nuclear Information System (INIS)

    Dudnikov, A. A.; Alekseev, P. N.; Subbotin, S. A.

    2007-01-01

    Creation fast critical molten salt reactor for burning-out minor actinides and separate long-living fission products in the closed nuclear fuel cycle is the most perspective and actual direction. The reactor on melts salts - molten salt homogeneous reactor with the circulating fuel, working as burner and transmuter long-living radioactive nuclides in closed nuclear fuel cycle, can serve as an effective ecological cordon from contamination of the nature long-living radiotoxic nuclides. High-flux fast critical molten-salt nuclear reactors in structure of the closed nuclear fuel cycle of the future nuclear power can effectively burning-out / transmute dangerous long-living radioactive nuclides, make radioisotopes, partially utilize plutonium and produce thermal and electric energy. Such reactor allows solving the problems constraining development of large-scale nuclear power, including fueling, minimization of radioactive waste and non-proliferation. Burning minor actinides in molten salt reactor is capable to facilitate work solid fuel power reactors in system NP with the closed nuclear fuel cycle and to reduce transient losses at processing and fabrications fuel pins. At substantiation MSR-transmuter/burner as solvents fuel nuclides for molten-salt reactors various salts were examined, for example: LiF - BeF2; NaF - LiF - BeF2; NaF-LiF ; NaF-ZrF4 ; LiF-NaF -KF; NaCl. RRC 'Kurchatov institute' together with other employees have developed the basic design reactor installations with molten salt reactor - burner long-living nuclides for fluoride fuel composition with the limited solubility minor actinides (MAF3 10 mol %) allows to develop in some times more effective molten salt reactor with fast neutron spectrum - burner/ transmuter of the long-living radioactive waste. In high-flux fast reactors on melts salts within a year it is possible to burn ∼300 kg minor actinides per 1 GW thermal power of reactor. The technical and economic estimation given power

  19. Parametric study of natural circulation flow in molten salt fuel in molten salt reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pauzi, Anas Muhamad, E-mail: Anas@uniten.edu.my [Centre of Nuclear Energy, Universiti Tenaga Nasional (UNITEN), Jalan IKRAM-UNITEN, 43000 Kajang, Selangor (Malaysia); Cioncolini, Andrea; Iacovides, Hector [School of Mechanical, Aerospace, and Civil Engineering (MACE), University of Manchester, Oxford Road, M13 9PL Manchester (United Kingdom)

    2015-04-29

    The Molten Salt Reactor (MSR) is one of the most promising system proposed by Generation IV Forum (GIF) for future nuclear reactor systems. Advantages of the MSR are significantly larger compared to other reactor system, and is mainly achieved from its liquid nature of fuel and coolant. Further improvement to this system, which is a natural circulating molten fuel salt inside its tube in the reactor core is proposed, to achieve advantages of reducing and simplifying the MSR design proposed by GIF. Thermal hydraulic analysis on the proposed system was completed using a commercial computation fluid dynamics (CFD) software called FLUENT by ANSYS Inc. An understanding on theory behind this unique natural circulation flow inside the tube caused by fission heat generated in molten fuel salt and tube cooling was briefly introduced. Currently, no commercial CFD software could perfectly simulate natural circulation flow, hence, modeling this flow problem in FLUENT is introduced and analyzed to obtain best simulation results. Results obtained demonstrate the existence of periodical transient nature of flow problem, hence improvements in tube design is proposed based on the analysis on temperature and velocity profile. Results show that the proposed system could operate at up to 750MW core power, given that turbulence are enhanced throughout flow region, and precise molten fuel salt physical properties could be defined. At the request of the authors and the Proceedings Editor the name of the co-author Andrea Cioncolini was corrected from Andrea Coincolini. The same name correction was made in the Acknowledgement section on page 030004-10 and in reference number 4. The updated article was published on 11 May 2015.

  20. Petrology of the 1995/2000 Magma of Copahue, Argentina

    Science.gov (United States)

    Goss, A.; Varekamp, J. C.

    2001-05-01

    Phreatomagmatic eruptions of Copahue in July/August,1995 and July/August 2000 produced mixed juvenile clasts, silica-rich debris from the hydrothermal system, and magmatic scoria with 88 percent SiO2. These high-SiO2 clasts carry an as yet unidentified (crystobalite?), euhedral silica phase in great abundance, which is riddled with tan, primary melt inclusions. The mixed clasts have bands of mafic material with small euhedral olivine, clinopyroxene, and plagioclase that are mixed with an intermediate magma with coarser, resorbed phenocrysts of olivine, plagioclase, clino- and ortho- pyroxene, and rare occurrences of the silica phase. These ejecta are intimate mixtures of a relatively felsic magma similar to Pleistocene Copahue lavas and a mafic basaltic andesite, with minor contributions of a magma contaminated with silica-rich hydrothermal wallrock material. Two-pyroxene geothermometry indicates crystallization temperatures of 1020 deg - 1045 deg C. Glass inclusions (59-63 percent SiO2) in plagioclase and olivine crystals yield very low volatile contents in the melt (0.4-1.5 percent H2O). The 1995/2000 magmas resided at shallow level and degassed into the active volcano-hydrothermal system which discharges acid fluids into the Copahue crater lake and hot springs. More mafic magma intruded this shallow batch and the mixture rose into the hydrothermal system and assimilated siliceous wall rock. A Ti-diffusion profile in a magnetite crystal suggests that the period between magma mixing and eruption was on the order of 4-10 weeks, and the temperature difference between resident and intruding magma was about 50-60 oC.

  1. Thirteen million years of silicic magma production in Iceland: Links between petrogenesis and tectonic settings

    Science.gov (United States)

    Martin, E.; Sigmarsson, O.

    2010-04-01

    The origin of the Quaternary silicic rocks in Iceland is thought to be linked to the thermal state of the crust, which in turn depends on the regional tectonic settings. This simple model is tested here on rocks from the Miocene to present, both to suggest an internally consistent model for silicic magma formation in Iceland and to constrain the link between tectonic settings and silicic magma petrogenesis. New major and trace-element compositions together with O-, Sr- and Nd-isotope ratios have been obtained on silicic rocks from 19 volcanic systems ranging in age from 13 Ma to present. This allows us to trace the spatial and temporal evolution of both magma generation and the corresponding sources. Low δ18O (geothermal gradient. But later than 5.5 Ma they were produced in a flank zone environment by fractional crystallisation alone, probably due to decreasing geothermal gradient, of basalts derived from a mantle source with lower 143Nd/ 144Nd. This is in agreement with an eastwards rift-jump, from Snæfellsnes towards the present Reykjanes Rift Zone, between 7 and 5.5 Ma. In the South Iceland Volcanic Zone (SIVZ), the intermediate Nd-signature observed in silicic rocks from the Torfajökull central volcano reflects the transitional character of the basalts erupted at this propagating rift segment. Therefore, the abundant evolved rocks at this major silicic complex result from partial melting of the transitional alkaline basaltic crust (Iceland can, therefore, be used for deciphering past geodynamic settings characterized by rift- and off-rift zones resulting from interaction of a mantle plume and divergent plate boundaries.

  2. A rapid mechanism to remobilize and homogenize highly crystalline magma bodies.

    Science.gov (United States)

    Burgisser, Alain; Bergantz, George W

    2011-03-10

    The largest products of magmatic activity on Earth, the great bodies of granite and their corresponding large eruptions, have a dual nature: homogeneity at the large scale and spatial and temporal heterogeneity at the small scale. This duality calls for a mechanism that selectively removes the large-scale heterogeneities associated with the incremental assembly of these magmatic systems and yet occurs rapidly despite crystal-rich, viscous conditions seemingly resistant to mixing. Here we show that a simple dynamic template can unify a wide range of apparently contradictory observations from both large plutonic bodies and volcanic systems by a mechanism of rapid remobilization (unzipping) of highly viscous crystal-rich mushes. We demonstrate that this remobilization can lead to rapid overturn and produce the observed juxtaposition of magmatic materials with very disparate ages and complex chemical zoning. What distinguishes our model is the recognition that the process has two stages. Initially, a stiff mushy magma is reheated from below, producing a reduction in crystallinity that leads to the growth of a subjacent buoyant mobile layer. When the thickening mobile layer becomes sufficiently buoyant, it penetrates the overlying viscous mushy magma. This second stage rapidly exports homogenized material from the lower mobile layer to the top of the system, and leads to partial overturn within the viscous mush itself as an additional mechanism of mixing. Model outputs illustrate that unzipping can rapidly produce large amounts of mobile magma available for eruption. The agreement between calculated and observed unzipping rates for historical eruptions at Pinatubo and at Montserrat demonstrates the general applicability of the model. This mechanism furthers our understanding of both the formation of periodically homogenized plutons (crust building) and of ignimbrites by large eruptions.

  3. Lithospheric controls on magma composition along Earth's longest continental hotspot track.

    Science.gov (United States)

    Davies, D R; Rawlinson, N; Iaffaldano, G; Campbell, I H

    2015-09-24

    Hotspots are anomalous regions of volcanism at Earth's surface that show no obvious association with tectonic plate boundaries. Classic examples include the Hawaiian-Emperor chain and the Yellowstone-Snake River Plain province. The majority are believed to form as Earth's tectonic plates move over long-lived mantle plumes: buoyant upwellings that bring hot material from Earth's deep mantle to its surface. It has long been recognized that lithospheric thickness limits the rise height of plumes and, thereby, their minimum melting pressure. It should, therefore, have a controlling influence on the geochemistry of plume-related magmas, although unambiguous evidence of this has, so far, been lacking. Here we integrate observational constraints from surface geology, geochronology, plate-motion reconstructions, geochemistry and seismology to ascertain plume melting depths beneath Earth's longest continental hotspot track, a 2,000-kilometre-long track in eastern Australia that displays a record of volcanic activity between 33 and 9 million years ago, which we call the Cosgrove track. Our analyses highlight a strong correlation between lithospheric thickness and magma composition along this track, with: (1) standard basaltic compositions in regions where lithospheric thickness is less than 110 kilometres; (2) volcanic gaps in regions where lithospheric thickness exceeds 150 kilometres; and (3) low-volume, leucitite-bearing volcanism in regions of intermediate lithospheric thickness. Trace-element concentrations from samples along this track support the notion that these compositional variations result from different degrees of partial melting, which is controlled by the thickness of overlying lithosphere. Our results place the first observational constraints on the sub-continental melting depth of mantle plumes and provide direct evidence that lithospheric thickness has a dominant influence on the volume and chemical composition of plume-derived magmas.

  4. Fast Thorium Molten Salt Reactors Started with Plutonium

    International Nuclear Information System (INIS)

    Merle-Lucotte, E.; Heuer, D.; Le Brun, C.; Brissot, R.; Liatard, E.; Meplan, O.; Nuttin, A.; Mathieu, L.

    2006-01-01

    One of the pending questions concerning Molten Salt Reactors based on the 232 Th/ 233 U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since 233 U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing 233 U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce 233 U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/ 233 U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into 233 U. A particular reactor configuration is used, called 'unique channel' configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Molten Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactor's characteristics turn out to be equivalent to Molten Salt Reactors operated with 233 U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with 233 U, the deployment capabilities of these reactors fully satisfy the condition of sustainability. (authors)

  5. Multistage unfolding of an SH3 domain: an initial urea-filled dry molten globule precedes a wet molten globule with non-native structure.

    Science.gov (United States)

    Dasgupta, Amrita; Udgaonkar, Jayant B; Das, Payel

    2014-06-19

    The unfolding of the SH3 domain of the PI3 kinase in aqueous urea has been studied using a synergistic experiment-simulation approach. The experimental observation of a transient wet molten globule intermediate, IU, with an unusual non-native burial of the sole Trp residue, W53, provides the benchmark for the unfolding simulations performed (eight in total, each at least 0.5 μs long). The simulations reveal that the partially unfolded IU ensemble is preceded by an early native-like molten globule intermediate ensemble I*. In the very initial stage of unfolding, dry globule conformations with the protein core filled with urea instead of water are transiently observed within the I* ensemble. Water penetration into the urea-filled core of dry globule conformations is frequently accompanied by very transient burial of W53. Later during gradual unfolding, W53 is seen to again become transiently buried in the IU ensemble for a much longer time. In the structurally heterogeneous IU ensemble, conformational flexibility of the C-terminal β-strands enables W53 burial by the formation of non-native, tertiary contacts with hydrophobic residues, which could serve to protect the protein from aggregation during unfolding.

  6. Corrosion study in molten fluoride salt

    International Nuclear Information System (INIS)

    Keny, S.J.; Kumbhar, A.G.; Rangarajan, S.; Gupta, V.K.; Maheshwari, N.K.; Vijayan, P.K.

    2013-01-01

    Corrosion behaviors of two alloys viz. Inconel 625 and Inconel 617 were tested in molten fluoride salts of lithium, sodium and potassium (FLiNaK) in the temperature range of 550-750 ℃ in a nickel lined Inconel vessel. Electrochemical polarization (Tafel plot) technique was used for this purpose. For both alloys, the corrosion rate was found to increase sharply beyond 650 ℃ . At 600 ℃ , Inconel 625 showed a decreasing trend in the corrosion rate over a period of 24 hours, probably due to changes in the surface conditions. After fifteen days, re-testing of Inconel 625 in the same melt showed an increase in the corrosion rate. Inconel 625 was found to be more corrosion resistant than Inconel 617. (author)

  7. The Integral Molten Salt Reactor (IMSR)

    Energy Technology Data Exchange (ETDEWEB)

    Leblanc, D. [Terrestrial Energy, Mississauga, Ontario (Canada)

    2014-12-15

    The Integral Molten Salt Reactor is a simple burner or converter design that seeks to maximize passive and inherent safety features in order to minimize development time and achieve true cost innovation. Its integration of all primary systems into a unit sealed for the design life of the reactor will be reviewed with focus on the unique design aspects that make this a pragmatic approach. The IMSR is being developed by Terrestrial Energy in a range of power outputs with initial focus on an 80 MWth (32.5 MWe) unit primarily for remote energy needs. Similar units of modestly larger dimension and up to 600 MWth (291 MWe) are planned that remain truck transportable and able to compete in base load electricity markets worldwide. (author)

  8. The Integral Molten Salt Reactor (IMSR)

    Energy Technology Data Exchange (ETDEWEB)

    LeBlanc, D., E-mail: dleblanc@terrestrialenergy.com [Terrestrial Energy, Mississauga, Ontario (Canada)

    2014-07-01

    The Integral Molten Salt Reactor is a simple burner or converter design that seeks to maximize passive and inherent safety features in order to minimize development time and achieve true cost innovation. Its integration of all primary systems into a unit sealed for the design life of the reactor will be reviewed with focus on the unique design aspects that make this a pragmatic approach. The IMSR is being developed by Terrestrial Energy in a range of power outputs with initial focus on an 80 MWth (32.5 MWe) unit primarily for remote energy needs. Similar units of modestly larger dimension and up to 600 MWth (291 MWe) are planned that remain truck transportable and able to compete in base load electricity markets worldwide. (author)

  9. Terrestrial Energy bets on molten salt reactors

    International Nuclear Information System (INIS)

    Anon.

    2015-01-01

    Terrestrial Energy is a Canadian enterprise, founded in 2013, for marketing the integral molten salt reactor (IMSR). A first prototype (called MSRE and with an energy output of 8 MW) was designed and operated between 1965 and 1969 by the Oak Ridge National Laboratory. IMSR is a small, modular reactor with a thermal energy output of 400 MW. According to Terrestrial Energy the technology of conventional power reactors is too complicated and too expensive. On the contrary IMSR's technology appears to be simple, easy to operate and affordable. With a staff of 30 people Terrestrial Energy appears to be a start-up in the nuclear sector. A process of pre-licensing will be launched in 2016 with the Canadian nuclear safety authority. (A.C.)

  10. Fuel processing for molten-salt reactors

    International Nuclear Information System (INIS)

    Hightower, J.R. Jr.

    1975-01-01

    Progress is reported on the development of processes for the isolation of protactinium and for the removal of fission products from molten-salt breeder reactors. The metal transfer experiment MTE-3 (for removing rare earths from MSRE fuel salt) was completed and the equipment used in that experiment was examined. The examination showed that no serious corrosion had occurred on the internal surfaces of the vessels, but that serious air oxidation occurred on the external surfaces of the vessels. Analyses of the bismuth phases indicated that the surfaces in contact with the salts were enriched in thorium and iron. Mass transfer coefficients in the mechanically agitated nondispersing contactors were measured in the Salt/Bismuth Flow-through Facility. The measured mass transfer coefficients are about 30 to 40 percent of those predicted by the preferred literature correlation, but were not as low as those seen in some of the runs in MTE-3. Additional studies using water--mercury systems to simulate molten salt-bismuth systems indicated that the model used to interpret results from previous measurements in the water--mercury system has significant deficiencies. Autoresistance heating studies were continued to develop a means of internal heat generation for frozen-wall fluorinators. Equipment was built to test a design of a side arm for the heating electrode. Results of experiments with this equipment indicate that for proper operation the wall temperature must be held much lower than that for which the equipment was designed. Studies with an electrical analog of the equipment indicate that no regions of abnormally high current density exist in the side arm. (JGB)

  11. Fast Spectrum Molten Salt Reactor Options

    Energy Technology Data Exchange (ETDEWEB)

    Gehin, Jess C [ORNL; Holcomb, David Eugene [ORNL; Flanagan, George F [ORNL; Patton, Bruce W [ORNL; Howard, Rob L [ORNL; Harrison, Thomas J [ORNL

    2011-07-01

    During 2010, fast-spectrum molten-salt reactors (FS-MSRs) were selected as a transformational reactor concept for light-water reactor (LWR)-derived heavy actinide disposition by the Department of Energy-Nuclear Energy Advanced Reactor Concepts (ARC) program and were the subject of a preliminary scoping investigation. Much of the reactor description information presented in this report derives from the preliminary studies performed for the ARC project. This report, however, has a somewhat broader scope-providing a conceptual overview of the characteristics and design options for FS-MSRs. It does not present in-depth evaluation of any FS-MSR particular characteristic, but instead provides an overview of all of the major reactor system technologies and characteristics, including the technology developments since the end of major molten salt reactor (MSR) development efforts in the 1970s. This report first presents a historical overview of the FS-MSR technology and describes the innovative characteristics of an FS-MSR. Next, it provides an overview of possible reactor configurations. The following design features/options and performance considerations are described including: (1) reactor salt options-both chloride and fluoride salts; (2) the impact of changing the carrier salt and actinide concentration on conversion ratio; (3) the conversion ratio; (4) an overview of the fuel salt chemical processing; (5) potential power cycles and hydrogen production options; and (6) overview of the performance characteristics of FS-MSRs, including general comparative metrics with LWRs. The conceptual-level evaluation includes resource sustainability, proliferation resistance, economics, and safety. The report concludes with a description of the work necessary to begin more detailed evaluation of FS-MSRs as a realistic reactor and fuel cycle option.

  12. Electrochemical surface nitriding of pure iron by molten salt electrochemical process

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimura, Hiroyuki; Goto, Takuya; Ito, Yasuhiko

    2004-08-11

    Electrochemical surface nitriding of pure iron was investigated in molten LiCl-KCl-Li{sub 3}N systems at 773 K. An outer compound layer and an inner diffusion layer were obtained by means of potentiostatic electrolysis at 1.00 V (versus Li{sup +}/Li). From XRD and SEM analyses, it was confirmed that the obtained compound layer consisted of {epsilon}-Fe{sub 2-3}N and {gamma}'-Fe{sub 4}N; the free energies of formation of the two nitrides are positive and the equilibrium nitrogen partial pressure of those are of the order of 10{sup 4} atm at 773 K. This result suggests that an apparent nitrogen partial pressure of at least the order of 10{sup 4} atm was imposed by the adsorbed nitrogen atoms (N{sub ads}) formed by anodic oxidation of nitride ion (N{sup 3-}) at the iron electrode surface.

  13. Novel waste printed circuit board recycling process with molten salt

    OpenAIRE

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450?470??C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, a...

  14. Mechanical structure and problem of thorium molten salt reactor

    International Nuclear Information System (INIS)

    Kamei, Takashi

    2011-01-01

    After Fukushima Daiichi accident, there became great interest in Thorium Molten Salt Reactor (MSR) for the safety as station blackout leading to auto drainage of molten salts with freeze valve. This article described mechanical structure of MSR and problems of materials and pipes. Material corrosion problem by molten salts would be solved using modified Hastelloy N with Ti and Nb added, which should be confirmed by operation of an experimental reactor. Trends in international activities of MSR were also referred including China declaring MSR development in January 2011 to solve thorium contamination issues at rare earth production and India rich in thorium resources. (T. Tanaka)

  15. Indian programme on molten salt cooled nuclear reactors

    International Nuclear Information System (INIS)

    DuIera, I.V.; Vijayan, P.K.; Sinha, R.K.

    2013-01-01

    Bhabha Atomic Research Centre (BARC) is developing a 600 MWth pebble bed high temperature reactor, cooled by natural circulation of molten fluoride salts and is capable of supplying process heat at 1000 ℃ to facilitate hydrogen production by splitting water. BARC has also initiated studies for a reactor concept in which salts of molten fluoride fuel and coolant in fluid form, flows through the reactor core of graphite moderator, resulting in nuclear fission within the molten salt. For thorium fuel cycle, this concept is very attractive, since the fuel can be re-processed on-line, enabling it to be an efficient neutron breeder. (author)

  16. Carbon dioxide in magmas and implications for hydrothermal systems

    Science.gov (United States)

    Lowenstern, J. B.

    2001-01-01

    This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-hydrothermal systems, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in hydrothermal systems

  17. Magma Transport from Deep to Shallow Crust and Eruption

    Science.gov (United States)

    White, R. S.; Greenfield, T. S.; Green, R. G.; Brandsdottir, B.; Hudson, T.; Woods, J.; Donaldson, C.; Ágústsdóttir, T.

    2016-12-01

    We have mapped magma transport paths from the deep (20 km) to the shallow (6 km) crust and in two cases to eventual surface eruption under several Icelandic volcanoes (Askja, Bardarbunga, Eyjafjallajokull, Upptyppingar). We use microearthquakes caused by brittle fracture to map magma on the move and tomographic seismic studies of velocity perturbations beneath volcanoes to map the magma storage regions. High-frequency brittle failure earthquakes with magnitudes of typically 0-2 occur where melt is forcing its way through the country rock, or where previously frozen melt is repeatedly re-broken in conduits and dykes. The Icelandic crust on the rift zones where these earthquakes occur is ductile at depths greater than 7 km beneath the surface, so the occurrence of brittle failure seismicity at depths as great as 20 km is indicative of high strain rates, for which magma movement is the most likely explanation. We suggest that high volatile pressures caused by the exsolution of carbon dioxide in the deep crust is driving the magma movement and seismicity at depths of 15-20 km. Eruptions from shallow crustal storage areas are likewise driven by volatile exsolution, though additional volatiles, and in particular water are also involved in the shallow crust.

  18. Duration of a Magma Ocean and Subsequent Mantle Overturn in Mars: Evidence from Nakhlites

    Science.gov (United States)

    Debaille, V.; Brandon, A. D.; Yin, Q.-Z.; Jacobsen, B.

    2008-01-01

    It is now generally accepted that the heat produced by accretion, short-lived radioactive elements such as Al-26, and gravitational energy from core formation was sufficient to at least partially melt the silicate portions of terrestrial planets resulting in a global-scale magma ocean. More particularly, in Mars, the geochemical signatures displayed by shergottites, are likely inherited from the crystallization of this magma ocean. Using the short-lived chronometer Sm-146 - Nd-142 (t(sup 1/2) = 103 Myr), the duration of the Martian magma ocean (MMO) has been evaluated to being less than 40 Myr, while recent and more precise ND-142/ND-144 data were used to evaluate the longevity of the MMO to approximately 100 Myr after the solar system formation. In addition, it has been proposed that the end of the crystallization of the MMO may have triggered a mantle overturn, as a result of a density gradient in the cumulate layers crystallized at different levels. Dating the mantle overturn could hence provide additional constraint on the duration of the MMO. Among SNC meteorites, nakhlites are characterized by high epsilon W-182 of approximately +3 and an epsilon Nd-142 similar to depleted shergottites of +0.6-0.9. It has hence been proposed that the source of nakhlites was established very early in Mars history (approximately 8-10 Myr). However, the times recorded in HF-182-W-182 isotope system, i.e. when 182Hf became effectively extinct (approximately 50 Myr after solar system formation) are less than closure times recorded in the Sm-146-Nd-142 isotope system (with a full coverage of approximately 500 Myr after solar system formation). This could result in decoupling between the present-day measured epsilon W-182 and epsilon Nd-142 as the SM-146 may have recorded later differentiation events in epsilon ND-142 not observed in epsilon W-182 values. With these potential complexities in short-lived chronological data for SNC's in mind, new Hf-176/Hf-177, Nd-143/Nd-144 and Nd

  19. Using fumarolic inert gas composition to investigate magma dynamics at Campi Flegrei (Italy)

    Science.gov (United States)

    Chiodini, G.; Caliro, S.; Paonita, A.; Cardellini, C.

    2013-12-01

    Since 2000 the Campi Flegrei caldera sited in Neapolitan area (Italy), has showed signs of reactivation, marked by ground uplift, seismic activity, compositional variations of fumarolic effluents from La Solfatara, an increase of the fumarolic activity as well as of soil CO2 fluxes. Comparing long time series of geochemical signals with ground deformation and seismicity, we show that these changes are at least partially caused by repeated injections of magmatic fluid into the hydrothermal system. The frequency of these degassing episodes has increased in the last years, causing pulsed uplift episodes and swarms of low magnitude earthquakes. We focus here in the inert gas species (CO2-He-Ar-N2) of Solfatara fumaroles which displayed in the time spectacular and persistent variation trends affecting all the monitored vents. The observed variations, which include a continuous decrease of both N2/He and N2/CO2 ratios since 1985, paralleled by an increase of He/CO2, can not be explained neither with changes in processes of boiling-condensation in the local hydrothermal system nor with changes in the mixing proportions between a magmatic vapour and hydrothermal fluids. Consequently we investigated the possibility that the trends of inert gas species are governed by changes in the conditions controlling magma degassing at depth. We applied a magma degassing model, with the most recent updates for inert gas solubilities, after to have included petrologic constraints from the ranges of melt composition and reservoir pressure at Campi Flegrei. The model simulations for mafic melts (trachybasalt and shoshonite) show a surprising agreement with the measured data. Both decompressive degassing of an ascending magma and mixing between magmatic fluids exsolved at various levels along the ascent path can explain the long-time geochemical changes. Our work highlights that, in caldera systems where the presence of hydrothermal aquifers commonly masks the magmatic signature of reactive

  20. On magma fragmentation by conduit shear stress: Evidence from the Kos Plateau Tuff, Aegean Volcanic Arc

    Science.gov (United States)

    Palladino, Danilo M.; Simei, Silvia; Kyriakopoulos, Konstantinos

    2008-12-01

    Large silicic explosive eruptions are the most catastrophic volcanic events. Yet, the intratelluric mechanisms underlying are not fully understood. Here we report a field and laboratory study of the Kos Plateau Tuff (KPT, 161 ka, Aegean Volcanic Arc), which provides an excellent geological example of conduit processes that control magma vesiculation and fragmentation during intermediate- to large-scale caldera-forming eruptions. A prominent feature of the KPT is the occurrence of quite unusual platy-shaped tube pumice clasts in pyroclastic fall and current deposits from the early eruption phases preceding caldera collapse. On macroscopic and SEM observations, flat clast faces are elongated parallel to tube vesicles, while transverse surfaces often occur at ~ 45° to vesicle elongation. This peculiar pumice texture provides evidence of high shear stresses related to strong velocity gradients normal to conduit walls, which induced vesiculation and fragmentation of the ascending magma. Either an increasing mass discharge rate without adequate enlargement of a narrow central feeder conduit or a developing fissure-like feeder system related to incipient caldera collapse provided suitable conditions for the generation of plate tube pumice within magma volumes under high shear during the pre-climactic KPT eruption phases. This mechanism implies that the closer to the conduit walls (where the stronger are the velocity gradients) the larger was the proportion of plate vs. conventional (lensoid) juvenile fragments in the ascending gas-pyroclast mixture. Consequently, plate pumice clasts were mainly entrained in the outer portions of the jet and convecting regions of a sustained, Plinian-type, eruption column, as well as in occasional lateral blast currents generated at the vent. As a whole, plate pumice clasts in the peripheral portions of the column were transported at lower altitudes and deposited by fallout or partial collapse closer to the vent relative to lensoid ones

  1. Magma storage in a strike-slip caldera.

    Science.gov (United States)

    Saxby, J; Gottsmann, J; Cashman, K; Gutiérrez, E

    2016-07-22

    Silicic calderas form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in caldera-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango caldera, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the caldera is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.

  2. What can Fe stable isotopes tell us about magmas?

    DEFF Research Database (Denmark)

    Stausberg, Niklas

    the differentiation of magmas from the perspective of Fe stable isotopes, integrated with petrology, by studying igneous rocks and their constituent phases (minerals and glasses) from the Bushveld Complex, South Africa, Thingmuli, Iceland, Pantelleria, Italy, and the Bishop Tuff, USA. The findings are interpreted......The majority of the Earth’s crust is formed by magmas, and understanding their production and differentiation is important to interpret the geologic rock record. A powerful tool to investigate magmatic processes is the distribution of the stable isotopes of the major redox-sensitive element...... in magmas, Fe. Fe isotope compositions of magmatic rocks exhibit systematic differences, where the heaviest compositions are found in rhyolites and granites. Understanding of these systematics is complicated by a lack of constraints on Fe isotope fractionation among minerals and liquids under magmatic...

  3. The magma ocean as an impediment to lunar plate tectonics

    Science.gov (United States)

    Warren, Paul H.

    1993-01-01

    The primary impediment to plate tectonics on the moon was probably the great thickness of its crust and particularly its high crust/lithosphere thickness ratio. This in turn can be attributed to the preponderance of low-density feldspar over all other Al-compatible phases in the lunar interior. During the magma ocean epoch, the moon's crust/lithosphere thickness ratio was at the maximum theoretical value, approximately 1, and it remained high for a long time afterwards. A few large regions of thin crust were produced by basin-scale cratering approximately contemporaneous with the demise of the magma ocean. However, these regions probably also tend to have uncommonly thin lithosphere, since they were directly heated and indirectly enriched in K, Th, and U by the same cratering process. Thus, plate tectonics on the moon in the form of systematic lithosphere subduction was impeded by the magma ocean.

  4. Phenomena associated with magma expansion into a drift

    International Nuclear Information System (INIS)

    Gaffney, E.S.

    2002-01-01

    One of the significant threats to the proposed Yucca Mountain nuclear waste repository has been identified as the possibility of intersection of the underground structure by a basaltic intrusion. Based on the geology of the region, it is assumed that such an intrusion would consist of an alkali basalt similar to the nearby Lathrop Wells cone, which has been dated at about 78 ka. The threat of radioactive release may be either from eruption through the surface above the repository of basalt that had been contaminated or from migration through ground water of radionucleides released as a result of damage to waste packages that interact with the magma. As part of our study of these threats, we are analyzing the phenomena associated with magma expansion into drifts in tuff. The early phenomena of the encounter of volatile-rich basaltic magma with a drift are discussed here.

  5. Complexities in Shallow Magma Transport at Kilauea (Invited)

    Science.gov (United States)

    Swanson, D. A.

    2013-12-01

    The standard model of Kilauea's shallow plumbing system includes magma storage under the caldera and conduits in the southwest rift zone (SWRZ) and the east rift zone (ERZ). As a field geologist, I find that seemingly aberrant locations and trends of some eruptive vents indicate complexities in shallow magma transport not addressed by the standard model. This model is not wrong but instead incomplete, because it does not account for the development of offshoots from the main plumbing. These offshoots supply magma to the surface at places that tell us much about the complicated stress system within the volcano. Perhaps most readily grasped are fissures peripheral to the north and south sides of the caldera. Somehow magma can apparently be injected into caldera-bounding faults from the summit reservoir complex, but the process and pathways are unclear. Of more importance is the presence of fissures with ENE trends on the east side of the caldera, including Kilauea Iki. Is this a rift zone that forms an acute angle with the ERZ? I think there is another explanation: the main part of the ERZ has migrated ~5 km SSE during the past few tens of thousands of years owing to seaward movement of the south flank, but older parts of the rift zone can be reactivated. The fissures east of the caldera have the ERZ trend and may record such reactivation; this interpretation includes the location of the largest eruption (15th century) known from Kilauea. Whether or not this interpretation has validity, the question remains: what changes in the plumbing system allow magma to erupt east of the caldera? The SWRZ can be divided into two sections, the SWRZ proper and the seismically active part (SASWRZ) southeast of the SWRZ. The total width of both sections is ~4 km. The SWRZ might be migrating SSE, as is the ERZ. Fissures in the SWRZ proper trend SW. Fissures in the SASWRZ, however, have ENE trends like that of the ERZ, although, because of en echelon offsets, the fissure zone itself

  6. Iron Redox Systematics of Shergottites and Martian Magmas

    Science.gov (United States)

    Righter, Kevin; Danielson, L. R.; Martin, A. M.; Newville, M.; Choi, Y.

    2010-01-01

    Martian meteorites record a range of oxygen fugacities from near the IW buffer to above FMQ buffer [1]. In terrestrial magmas, Fe(3+)/ SigmaFe for this fO2 range are between 0 and 0.25 [2]. Such variation will affect the stability of oxides, pyroxenes, and how the melt equilibrates with volatile species. An understanding of the variation of Fe(3+)/SigmaFe for martian magmas is lacking, and previous work has been on FeO-poor and Al2O3-rich terrestrial basalts. We have initiated a study of the iron redox systematics of martian magmas to better understand FeO and Fe2O3 stability, the stability of magnetite, and the low Ca/high Ca pyroxene [3] ratios observed at the surface.

  7. Fission product removal from molten salt using zeolite

    International Nuclear Information System (INIS)

    Pereira, C.; Babcock, B.D.

    1996-01-01

    Spent nuclear fuel (SNF) can be treated in a molten salt electrorefiner for conversion into metal and mineral waste forms for geologic disposal. The fuel is dissolved in molten chloride salt. Non-transuranic fission products in the molten salt are ion-exchanged into zeolite A, which is subsequently mixed with glass and consolidated. Zeolite was found to be effective in removing fission product cations from the molten salt. Breakthrough of cesium and the alkaline earths occurred more rapidly than was observed for the rare earths. The effluent composition as a function of time is presented, as well as results for the distribution of fission products along the length of the column. Effects of temperature and salt flow rate are also discussed

  8. Boric Ester-Type Molten Salt via Dehydrocoupling Reaction

    Directory of Open Access Journals (Sweden)

    Noriyoshi Matsumi

    2014-11-01

    Full Text Available Novel boric ester-type molten salt was prepared using 1-(2-hydroxyethyl-3-methylimidazolium chloride as a key starting material. After an ion exchange reaction of 1-(2-hydroxyethyl-3-methylimidazolium chloride with lithium (bis-(trifluoromethanesulfonyl imide (LiNTf2, the resulting 1-(2-hydroxyethyl-3-methylimidazolium NTf2 was reacted with 9-borabicyclo[3.3.1]nonane (9-BBN to give the desired boric ester-type molten salt in a moderate yield. The structure of the boric ester-type molten salt was supported by 1H-, 13C-, 11B- and 19F-NMR spectra. In the presence of two different kinds of lithium salts, the matrices showed an ionic conductivity in the range of 1.1 × 10−4–1.6 × 10−5 S cm−1 at 51 °C. This was higher than other organoboron molten salts ever reported.

  9. Dynamics and control of molten-salt breeder reactor

    Directory of Open Access Journals (Sweden)

    Vikram Singh

    2017-08-01

    Full Text Available Preliminary results of the dynamic analysis of a two-fluid molten-salt breeder reactor (MSBR system are presented. Based on an earlier work on the preliminary dynamic model of the concept, the model presented here is nonlinear and has been revised to accurately reflect the design exemplified in ORNL-4528. A brief overview of the model followed by results from simulations performed to validate the model is presented. Simulations illustrate stable behavior of the reactor dynamics and temperature feedback effects to reactivity excursions. Stable and smooth changes at various nodal temperatures are also observed. Control strategies for molten-salt reactor operation are discussed, followed by an illustration of the open-loop load-following capability of the molten-salt breeder reactor system. It is observed that the molten-salt breeder reactor system exhibits “self-regulating” behavior, minimizing the need for external controller action for load-following maneuvers.

  10. Conceptual design of Indian molten salt breeder reactor

    International Nuclear Information System (INIS)

    Vijayan, P.K.; Basak, A.; Dulera, I.V.; Vaze, K.K.; Basu, S.; Sinha, R.K.

    2014-01-01

    The fuel in a molten salt breeder reactor is in the form of a continuously circulating molten salt. Fluoride based salts have been almost universally proposed. A crucial part for achieving reasonable breeding in such reactors is the need to reprocess the salt continuously, either online or in batch mode. This constitutes a major technological challenge for this type of reactors. India has recently started carrying out fundamental studies so as to arrive at a conceptual design of Indian Molten Salt Breeder Reactor (IMSBR). Presently various design options and possibilities are being studied from the point of view of reactor physics and thermal hydraulic design. In parallel fundamental studies as regards various molten salts have also been initiated. This paper would discuss conceptual design of these reactors, as well as associated issues and technologies

  11. Dynamics and control of molten-salt breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sing, Vikram; Lish, Matthew R.; Chvala, Ondrej; Upadhyaya, Belle R. [Dept. of Nuclear Engineering, University of Tennessee, Knoxville (United States)

    2017-08-15

    Preliminary results of the dynamic analysis of a two-fluid molten-salt breeder reactor (MSBR) system are presented. Based on an earlier work on the preliminary dynamic model of the concept, the model presented here is nonlinear and has been revised to accurately reflect the design exemplified in ORNL-4528. A brief overview of the model followed by results from simulations performed to validate the model is presented. Simulations illustrate stable behavior of the reactor dynamics and temperature feedback effects to reactivity excursions. Stable and smooth changes at various nodal temperatures are also observed. Control strategies for molten-salt reactor operation are discussed, followed by an illustration of the open-loop load-following capability of the molten-salt breeder reactor system. It is observed that the molten-salt breeder reactor system exhibits “self-regulating” behavior, minimizing the need for external controller action for load-following maneuvers.

  12. Advanced Additive Manufacturing Feedstock from Molten Regolith Electrolysis

    Data.gov (United States)

    National Aeronautics and Space Administration — Demonstrate the feasibility of Molten Regolith Electrolysis (MRE) Reactor start by initiating resistive-heating of the regolith past its melting point using...

  13. High Surface Iridium Anodes for Molten Oxide Electrolysis, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith...

  14. System Requirements Document for the Molten Salt Reactor Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Aigner, R.D.

    2000-04-01

    The purpose of the conversion process is to convert the {sup 233}U fluoride compounds that are being extracted from the Molten Salt Reactor Experiment (MSRE) equipment to a stable oxide for long-term storage at Bldg. 3019.

  15. Lunar Magma Ocean Crystallization: Constraints from Fractional Crystallization Experiments

    Science.gov (United States)

    Rapp, J. F.; Draper, D. S.

    2015-01-01

    The currently accepted paradigm of lunar formation is that of accretion from the ejecta of a giant impact, followed by crystallization of a global scale magma ocean. This model accounts for the formation of the anorthosite highlands crust, which is globally distributed and old, and the formation of the younger mare basalts which are derived from a source region that has experienced plagioclase extraction. Several attempts at modelling the crystallization of such a lunar magma ocean (LMO) have been made, but our ever-increasing knowledge of the lunar samples and surface have raised as many questions as these models have answered. Geodynamic models of lunar accretion suggest that shortly following accretion the bulk of the lunar mass was hot, likely at least above the solidus]. Models of LMO crystallization that assume a deep magma ocean are therefore geodynamically favorable, but they have been difficult to reconcile with a thick plagioclase-rich crust. A refractory element enriched bulk composition, a shallow magma ocean, or a combination of the two have been suggested as a way to produce enough plagioclase to account for the assumed thickness of the crust. Recently however, geophysical data from the GRAIL mission have indicated that the lunar anorthositic crust is not as thick as was initially estimated, which allows for both a deeper magma ocean and a bulk composition more similar to the terrestrial upper mantle. We report on experimental simulations of the fractional crystallization of a deep (approximately 100km) LMO with a terrestrial upper mantle-like (LPUM) bulk composition. Our experimental results will help to define the composition of the lunar crust and mantle cumulates, and allow us to consider important questions such as source regions of the mare basalts and Mg-suite, the role of mantle overturn after magma ocean crystallization and the nature of KREEP

  16. Molybdenite saturation in silicic magmas: Occurrence and petrological implications

    Science.gov (United States)

    Audetat, A.; Dolejs, D.; Lowenstern, J. B.

    2011-01-01

    We identified molybdenite (MoS2) as an accessory magmatic phase in 13 out of 27 felsic magma systems examined worldwide. The molybdenite occurs as small (molybdenite-saturated samples reveal 1-13 ppm Mo in the melt and geochemical signatures that imply a strong link to continental rift basalt-rhyolite associations. In contrast, arc-associated rhyolites are rarely molybdenite-saturated, despite similar Mo concentrations. This systematic dependence on tectonic setting seems to reflect the higher oxidation state of arc magmas compared with within-plate magmas. A thermodynamic model devised to investigate the effects of T, f O2 and f S2 on molybdenite solubility reliably predicts measured Mo concentrations in molybdenite-saturated samples if the magmas are assumed to have been saturated also in pyrrhotite. Whereas pyrrhotite microphenocrysts have been observed in some of these samples, they have not been observed from other molybdenite-bearing magmas. Based on the strong influence of f S2 on molybdenite solubility we calculate that also these latter magmas must have been at (or very close to) pyrrhotite saturation. In this case the Mo concentration of molybdenite-saturated melts can be used to constrain both magmatic f O2 and f S2 if temperature is known independently (e.g. by zircon saturation thermometry). Our model thus permits evaluation of magmatic f S2, which is an important variable but is difficult to estimate otherwise, particularly in slowly cooled rocks. ?? The Author 2011. Published by Oxford University Press. All rights reserved.

  17. Failed magmatic eruptions: Late-stage cessation of magma ascent

    Science.gov (United States)

    Moran, S.C.; Newhall, C.; Roman, D.C.

    2011-01-01

    When a volcano becomes restless, a primary question is whether the unrest will lead to an eruption. Here we recognize four possible outcomes of a magmatic intrusion: "deep intrusion", "shallow intrusion", "sluggish/viscous magmatic eruption", and "rapid, often explosive magmatic eruption". We define "failed eruptions" as instances in which magma reaches but does not pass the "shallow intrusion" stage, i. e., when magma gets close to, but does not reach, the surface. Competing factors act to promote or hinder the eventual eruption of a magma intrusion. Fresh intrusion from depth, high magma gas content, rapid ascent rates that leave little time for enroute degassing, opening of pathways, and sudden decompression near the surface all act to promote eruption, whereas decreased magma supply from depth, slow ascent, significant enroute degassing and associated increases in viscosity, and impingement on structural barriers all act to hinder eruption. All of these factors interact in complex ways with variable results, but often cause magma to stall at some depth before reaching the surface. Although certain precursory phenomena, such as rapidly escalating seismic swarms or rates of degassing or deformation, are good indicators that an eruption is likely, such phenomena have also been observed in association with intrusions that have ultimately failed to erupt. A perpetual difficulty with quantifying the probability of eruption is a lack of data, particularly on instances of failed eruptions. This difficulty is being addressed in part through the WOVOdat database. Papers in this volume will be an additional resource for scientists grappling with the issue of whether or not an episode of unrest will lead to a magmatic eruption.

  18. Density and Structure Analysis of Molten Ni-W Alloys

    Institute of Scientific and Technical Information of China (English)

    Feng XIAO; Liang FANG

    2004-01-01

    Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773~1873 K with a sessile drop method.The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.

  19. Molten fluoride mixtures as possible fission reactor fuels

    International Nuclear Information System (INIS)

    Grimes, W.R.

    1978-01-01

    Molten mixtures of fluorides with UF 4 as a component have been used as combined fuel and primary heat transfer agent in experimental high-temperature reactors and have been proposed for use in breeders or converters of 233 U from thorium. Such use places stringent and diverse demands upon the fluid fuel. A brief review of chemical behavior of molten fluorides is given to show some of their strengths and weaknesses for such service

  20. Internal cation mobilities in molten lithium. Potassium fluoride

    International Nuclear Information System (INIS)

    Matsuura, Haruaki; Ohashi, Ryo; Chou, Pao-Hwa; Takagi, Ryuzo

    2006-01-01

    Relative differences between internal cation mobilities in molten (Li, K) F have been measured by countercurrent electromigration (Klemm method) at 1023 K. Internal mobilities of K + are larger than those of Li + in all composition on which we have measured so far. More striking feature is that the isotherms have minimum of mobilities at ca. x K =0.5. The local structural parameters would be highly related to the ionic conduction behavior in molten fluorides. (author)

  1. Measurement of emittance of metal interface in molten salt

    International Nuclear Information System (INIS)

    Araki, N.; Makino, A.; Nakamura, Y.

    1995-01-01

    A new technique for measuring the total normal emittance of a metal in a semi-transparent liquid has been proposed and this technique has been applied to measure the emittance of stainless steel (SUS304), nickel, and gold in molten potassium nitrate KNO 3 . These emittance data are indispensable to analyzing the radiative heat transfer between a metal and a semitransparent liquid, such as a molten salt

  2. Orientation of the eruption fissures controlled by a shallow magma chamber in Miyakejima

    Directory of Open Access Journals (Sweden)

    Nobuo Geshi

    2016-11-01

    Full Text Available Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano indicate tectonic influence of a shallow magma chamber on the distribution of eruption fissures. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey and a new dataset of 14C ages. The dominant orientation of the eruption fissures in the central portion of the volcano was found to be NE-SW, which is perpendicular to the direction of regional maximum horizontal compressive stress (σHmax. Magmas that show evidences of magma mixing between basaltic and andesitic magmas erupted mainly from the eruption fissures with a higher offset angle from the regional σHmax direction. The presence of a shallow dike-shaped magma chamber controls the distribution of the eruption fissures. The injection of basaltic magma into the shallow andesitic magma chamber caused the temporal rise of internal magmatic pressure in the shallow magma chamber. Dikes extending from the andesitic magma chamber intrude along the local compressive stress field which is generated by the internal excess pressure of the andesitic magma chamber. As the result, the eruption fissures trend parallel to the elongation direction of the shallow magma chamber. Injection of basaltic magma into the shallow andesitic magma chamber caused the magma mixing. Some basaltic dikes from the deep-seated magma chamber reach the ground surface without intersection with the andesitic magma chamber. The patterns of the eruption fissures can be modified in the future as was observed in the case of the destruction of the shallow magma chamber during the 2000 AD eruption.

  3. Isotopic evidence for multiple contributions to felsic magma chambers

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Wiebe, R.A.; Krogstad, E.J.

    2007-01-01

    The Gouldsboro Granite forms part of the Coastal Maine Magmatic Province, a region characterized by granitic plutons that are intimately linked temporally and petrogenetically with abundant co-existing mafic magmas. The pluton is complex and preserves a felsic magma chamber underlain...... with identical isotopic compositions to more mafic dikes suggest that closed system fractionation may be occurring in deeper level chambers prior to injection to shallower levels. The granitic portion of the pluton has the highest Nd isotopic composition (eNd=+3.0) of plutons in the region whereas the mafic...

  4. Silicic magma differentiation in ascent conduits. Experimental constraints

    Science.gov (United States)

    Rodríguez, Carmen; Castro, Antonio

    2017-02-01

    Crystallization of water-bearing silicic magmas in a dynamic thermal boundary layer is reproduced experimentally by using the intrinsic thermal gradient of piston-cylinder assemblies. The standard AGV2 andesite under water-undersaturated conditions is set to crystallize in a dynamic thermal gradient of about 35 °C/mm in 10 mm length capsules. In the hotter area of the capsule, the temperature is initially set at 1200 °C and decreases by programmed cooling at two distinct rates of 0.6 and 9.6 °C/h. Experiments are conducted in horizontally arranged assemblies in a piston cylinder apparatus to avoid any effect of gravity settling and compaction of crystals in long duration runs. The results are conclusive about the effect of water-rich fluids that are expelled out the crystal-rich zone (mush), where water saturation is reached by second boiling in the interstitial liquid. Expelled fluids migrate to the magma ahead of the solidification front contributing to a progressive enrichment in the fluxed components SiO2, K2O and H2O. The composition of water-rich fluids is modelled by mass balance using the chemical composition of glasses (quenched melt). The results are the basis for a model of granite magma differentiation in thermally-zoned conduits with application of in-situ crystallization equations. The intriguing textural and compositional features of the typical autoliths, accompanying granodiorite-tonalite batholiths, can be explained following the results of this study, by critical phenomena leading to splitting of an initially homogeneous magma into two magma systems with sharp boundaries. Magma splitting in thermal boundary layers, formed at the margins of ascent conduits, may operate for several km distances during magma transport from deep sources at the lower crust or upper mantle. Accordingly, conduits may work as chromatographic columns contributing to increase the silica content of ascending magmas and, at the same time, leave behind residual mushes that

  5. Hydrogen permeation through Flinabe fluoride molten salts for blanket candidates

    Energy Technology Data Exchange (ETDEWEB)

    Nishiumi, Ryosuke, E-mail: r.nishiumi@aees.kyushu-u.ac.jp; Fukada, Satoshi; Nakamura, Akira; Katayama, Kazunari

    2016-11-01

    Highlights: • H{sub 2} diffusivity, solubility and permeability in Flinabe as T breeder are determined. • Effects in composition differences among Flibe, Fnabe and Flinabe are compared. • Changes of pressure dependence of Flinabe permeation rate are clarified. - Abstract: Fluoride molten salt Flibe (2LiF + BeF{sub 2}) is a promising candidate for the liquid blanket of a nuclear fusion reactor, because of its large advantages of tritium breeding ratio and heat-transfer fluid. Since its melting point is higher than other liquid candidates, another new fluoride molten salt Flinabe (LiF + NaF + BeF{sub 2}) is recently focused on because of its lower melting point while holding proper breeding properties. In this experiment, hydrogen permeation behavior through the three molten salts of Flibe (2LiF + BeF{sub 2}), Fnabe (NaF + BeF{sub 2}) and Flinabe are investigated in order to clarify the effects of their compositions on hydrogen transfer properties. After making up any of the three molten salts and purifying it using HF, hydrogen permeability, diffusivity and solubility of the molten salts are determined experimentally by using a system composed of tertiary cylindrical tubes. Close agreement is obtained between experimental data and analytical solutions. H{sub 2} permeability, diffusivity and solubility are correlated as a function of temperature and are compared among the three molten salts.

  6. Novel waste printed circuit board recycling process with molten salt.

    Science.gov (United States)

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450-470 °C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, allowing molten salt access from different depths for metal recovery. A laboratory scale batch reactor was constructed using 316L as suitable construction material. For safety reasons, the inert, stable LiCl-KCl molten salts were used as direct heat transfer fluid. Recovered materials were washed with hot water to remove residual salt before metal recovery assessment. The impact of this work was to show metal separation using molten salts in one single unit, by using this novel reactor methodology. •The reactor is a U-shaped reactor filled with a continuous liquid with a sloped bottom representing a novel reactor concept.•This method uses large PCB pieces instead of shredded PCBs as the reactor volume is 2.2 L.•The treated PCBs can be removed via leg B while the process is on-going.

  7. Novel waste printed circuit board recycling process with molten salt

    Science.gov (United States)

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450–470 °C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, allowing molten salt access from different depths for metal recovery. A laboratory scale batch reactor was constructed using 316L as suitable construction material. For safety reasons, the inert, stable LiCl–KCl molten salts were used as direct heat transfer fluid. Recovered materials were washed with hot water to remove residual salt before metal recovery assessment. The impact of this work was to show metal separation using molten salts in one single unit, by using this novel reactor methodology. • The reactor is a U-shaped reactor filled with a continuous liquid with a sloped bottom representing a novel reactor concept. • This method uses large PCB pieces instead of shredded PCBs as the reactor volume is 2.2 L. • The treated PCBs can be removed via leg B while the process is on-going. PMID:26150977

  8. Study on mechanical interaction between molten alloy and water

    International Nuclear Information System (INIS)

    Nishimura, Satoshi; Ueda, Nobuyuki; Nishi, Yoshihisa; Furuya, Masahiro; Kinoshita, Izumi

    1999-01-01

    Simulant experiments using low melting point molten alloy and water have been conducted to observe both fragmentation behavior of molten jet and boiling phenomena of water, and to measure both particle size and shape of fragmented solidified jet, focusing on post-pin-failure molten fuel-coolant interaction (FCl) which was important to evaluate the sequence of the initiating phase for metallic fueled FBR. In addition, characteristics of coolant boiling phenomena on FCIs have been investigated, focusing on the boiling heat transfer in the direct contact heat transfer mode. As a results, it is concluded that the fragmentation of poured molten alloy jet is affected by a degree of boiling of water and is classified into three modes by thermal conditions of both the instantaneous contact interface temperature of two liquids and subcooling of water. In the case of forced convection boiling in direct contact mode, it is found that the heat transfer performance is enhanced by increase of the heat transfer area, due to oscillation of the surface and fragmentation of molten alloy. As a results of preliminary investigation of FCI behavior for metallic fuel core based on these results, it is expected that the ejected molten fuel is fragmented into almost spherical particles due to the developed boiling of sodium. (author)

  9. Magnesium Isotopes as a Tracer of Crustal Materials in Volcanic Arc Magmas in the Northern Cascade Arc

    Directory of Open Access Journals (Sweden)

    Aaron W. Brewer

    2018-03-01

    Full Text Available Fifteen North Cascade Arc basalts and andesites were analyzed for Mg isotopes to investigate the extent and manner of crustal contributions to this magmatic system. The δ26Mg of these samples vary from within the range of ocean island basalts (the lightest being −0.33 ± 0.07‰ to heavier compositions (as heavy as −0.15 ± 0.06‰. The observed range in chemical and isotopic composition is similar to that of other volcanic arcs that have been assessed to date in the circum-pacific subduction zones and in the Caribbean. The heavy Mg isotope compositions are best explained by assimilation and fractional crystallization within the deep continental crust with a possible minor contribution from the addition of subducting slab-derived fluids to the primitive magma. The bulk mixing of sediment into the primitive magma or mantle source and the partial melting of garnet-rich peridotite are unlikely to have produced the observed range of Mg isotope compositions. The results show that Mg isotopes may be a useful tracer of crustal input into a magma, supplementing traditional methods such as radiogenic isotopic and trace element data, particularly in cases in which a high fraction of crustal material has been added.

  10. Coeval Formation of Zircon Megacrysts and Host Magmas in the Eifel Volcanic Field (Germany) Based on High Spatial Resolution Petrochronology

    Science.gov (United States)

    Schmitt, Axel; Klitzke, Malte; Gerdes, Axel; Ludwig, Thomas; Schäfer, Christof

    2017-04-01

    Zircon megacrysts (approx. 0.5-6 mm in diameter) from the Quaternary West and East Eifel volcanic fields, Germany, occur as euhedral crystals in porous K-spar rich plutonic ejecta clasts, and as partially resorbed xenocrysts in tephrite lava. Their relation to the host volcanic rocks has remained contentious because the dominantly basanitic to phonolitic magma compositions in the Eifel are typically zircon undersaturated. We carried out a detailed microanalytical study of zircon megacrysts from seven locations (Emmelberg and Rockeskyll in the West Eifel; Bellerberg, Laacher See, Mendig, Rieden, and Wehr in the East Eifel). Crystals were embedded in epoxy, sectioned to expose interiors through grinding with abrasives, diamond-polished, and mapped by optical microscopy, backscattered electron, and cathodoluminescence imaging. Subsequently, isotope-specific analysis using secondary ionization mass spectrometry (SIMS) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) was carried out placing 100 correlated spots on 20 selected crystals. Concordant U-Th disequilibrium and U-Pb ages determined by SIMS are between ca. 430 ka (Rieden) and 170 ka (Mendig) and indicate that the megacryst zircons crystallized almost always briefly before eruption. A significant gap between zircon megacryst crystallization (ca. 230 ka) and eruption (ca. 45 ka) ages was only detected for the Emmelberg location. SIMS trace element abundances (e.g., rare earth elements) vary by orders-of-magnitude and correlate with domain boundaries visible in cathodoluminescence; trace element patterns match those reported for zircon from syenitic origins. Isotopic compositions are homogeneous within individual crystals, but show some heterogeneity between different crystals from the same locality. Average isotopic values (δ18O SMOW = +5.3±0.6 ‰ by SIMS; present-day ɛHf = +1.7±2.5 ‰ by LA-ICP-MS; 1 standard deviation), however, are consistent with source magmas being dominantly mantle

  11. Geochronological and mineralogical constraints on depth of emplacement and ascencion rates of epidote-bearing magmas from northeastern Brazil

    Science.gov (United States)

    Sial, Alcides N.; Vasconcelos, Paulo M.; Ferreira, Valderez P.; Pessoa, Ricardo R.; Brasilino, Roberta G.; Morais Neto, João M.

    2008-10-01

    Calc-alkalic to high-K calc-alkalic granitoid plutons in the Borborema province, northeastern Brazil, have been studied to constrain depth of emplacement by mineralogical and geological methods and to estimate upward magma transport rate based on partial dissolution of magmatic epidote. Laser-probe incremental heating 40Ar/ 39Ar dating of biotite and hornblende single crystals from the Neoproterozoic Tavares and Brejinho high-K calc-alkalic magmatic epidote (mEp)-bearing plutons reveals age differences of around 60 M.y. between these two minerals in each of these two intrusions. These data suggest solidification at relatively great depth followed by prolonged cooling interval between the closure temperatures of biotite and hornblende. Al-in-hornblende barometry indicates that hornblende in several mEp-bearing plutons in the Transversal Domain of the Borborema province solidified at 5 to 7 kbar, whereas in the Seridó and Macururé terranes, solidification pressures range from 3 to 4 kbar. Partial dissolution of epidote indicates very rapid upward transport. Partial corrosion occurred during 15-35 years (Cachoerinha-Salgueiro terrane), 10-30 years (Alto Pajeú), 15 years (Seridó), and 10 years (Macururé) corresponding to upward transport rates of 450-1300, 650-1050, 1200, and 1800 m/year respectively in these four terranes. Rapid upward magma migration in most cases was probably facilitated by diking simultaneous with regional shearing.

  12. The Earth’s mantle before convection: Effects of magma oceans and the Moon (Invited)

    Science.gov (United States)

    Elkins-Tanton, L. T.; Smrekar, S. E.; Tobie, G.

    2009-12-01

    Studies of magma oceans indicate that planets obtain a gravitationally stable, compositionally differentiated mantle following solidification. This stable mantle results primarily from iron-magnesium partitioning during solidification, producing progressively iron-enriched mantle phases as solidification proceeds. Near the end of solidification, the dense solids will overturn to a stable configuration. The resulting differentiated mantle is stable from compositional density gradients that are significant enough to suppress thermal convection for up to hundreds of millions of years or longer, a scenario that proceeds self-consistently from physical and chemical principals, but is in contradiction with a previous image of a hot, turbulently convecting earliest terrestrial mantle. The isotopic range found in Martian meteorites indicates that its mantle differentiated in the first tens of millions of years of the solar system and has not been thoroughly remixed since. The specific isotopic range found on Mars is consistent with formation in a magma ocean. Based on the isotopic compositions of magmas, the Earth’s mantle is well mixed in comparison with the mantle of Mars. If the terrestrial planets experienced partial or whole magma oceans and thus began with stable mantles, resisting the onset of thermal convection and subsequent remixing, then why is Earth’s mantle well mixed? Two processes predicted to occur on the Earth, but not on the smaller Mars, may explain the divergent evolutions of these bodies. Here we will present model calculations for these two processes. First, we hypothesize that in the brief period that the Moon was very close to the Earth, it may have tidally heated Earth’s interior sufficiently to overcome its initial compositionally stable mantle, initiate active convection, and set the stage for the well-mixed mantle sampled today. Mars, conversely, may have cooled significantly before thermal convection began, allowing the formation of a

  13. Artificial magma program: Report on workshop held in Oak Ridge, Tennessee on March 29-30, 1994

    International Nuclear Information System (INIS)

    Naney, M.T.; Jacobs, G.K.

    1995-03-01

    A workshop was organized and conducted in Oak Ridge, Tennessee, on March 29 and 30, 1994, to evaluate the use of in situ vitrification (ISV) technology to produce large silicate melts that would serve as analogs for natural magmas for the study of magmatic properties and processes. ISV technology would permit experiments to test hypotheses or provide new data that cannot be tested or obtained through bench-top experimentation or the study of natural systems. The scale of ISV melts is intermediate between that of natural lava lakes and laboratory crucible experiments, with melt volumes from 15 to 300 m 3 easily obtained. This approach permits investigation of dynamic processes which operate on scales difficult to simulate through bench-top experimentation and that are not amenable to direct observation or control in natural systems (e.g., degassing, convection, and crystal settling). Several aspects of the ISV process make it uniquely applicable for the study of magma systems. The process produces open-quotes containerlessclose quotes silicate melts, which permits development of important analog components of natural magma systems including: partial melt zones, stopping, contact metamorphic haloes, and open-quotes hydrothermalclose quotes fluids. The lack of a melt open-quotes containerclose quotes also enables use of standard field-scale geophysical instrumentation for studying the seismic and electrical properties of the melt and host materials. In addition, volatile and particulate emissions from the melt can be sampled using methods that avoid reaction with, and contamination by, host rocks. The consensus of the group was that the use of melts generated by ISV technology provided unique opportunities to advance the understanding of magmas and magmatic processes and warranted development of a proposal

  14. Molten Salt Breeder Reactor Analysis Methods

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jinsu; Jeong, Yongjin; Lee, Deokjung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2015-05-15

    Utilizing the uranium-thorium fuel cycle shows considerable potential for the possibility of MSR. The concept of MSBR should be revised because of molten salt reactor's advantage such as outstanding neutron economy, possibility of continuous online reprocessing and refueling, a high level of inherent safety, and economic benefit by keeping off the fuel fabrication process. For the development of MSR research, this paper provides the MSBR single-cell, two-cell and whole core model for computer code input, and several calculation results including depletion calculation of each models. The calculations are carried out by using MCNP6, a Monte Carlo computer code, which has CINDER90 for depletion calculation using ENDF-VII nuclear data. From the calculation results of various reactor design parameters, the temperature coefficients are all negative at the initial state and MTC becomes positive at the equilibrium state. From the results of core rod worth, the graphite control rod alone cannot makes the core subcritical at initial state. But the equilibrium state, the core can be made subcritical state only by graphite control rods. Through the comparison of the results of each models, the two-cell method can represent the MSBR core model more accurately with a little more computational resources than the single-cell method. Many of the thermal spectrum MSR have adopted a multi-region single-fluid strategy.

  15. Fragmentation of molten core material by sodium

    International Nuclear Information System (INIS)

    Chu, T.Y.

    1982-01-01

    A series of scoping experiments was performed to study the fragmentation of prototypic high temperature melts in sodium. The quantity of melt involved was at least one order of magnitude larger than previous experiments. Two modes of contact were used: melt streaming into sodium and sodium into melt. The average bulk fragment size distribution was found to be in the range of previous data and the average size distribution was found to be insensitive to mode of contact. SEM studies showed that the metal component typically fragmented in the molten phase while the oxide component fragmented in the solid phase. For UO 2 -ZrO 2 /stainless steel melts no sigificant spatial separation of the metal and oxide was observed. The fragment size distribution was stratified vertically in the debris bed in all cases. While the bulk fragment size showed generally consistent trends, the individual experiments were sufficiently different to cause different degrees of stratification in the debris bed. For the highly stratified beds the permeability can decrease by as much as a factor of 20 from the bottom to the top of the bed

  16. Molten aluminum alloy fuel fragmentation experiments

    International Nuclear Information System (INIS)

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-01-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles (∼30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller (∼ mm), and the 20 mm jet which underwent sinuous wave breakup produced ∼100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was ≥343 K, the melt fragments did not freeze during their transit through 1.2 m of water

  17. Molten salt reactor related research in Switzerland

    International Nuclear Information System (INIS)

    Krepel, Jiri; Hombourger, Boris; Fiorina, Carlo

    2015-01-01

    Switzerland represented by the Paul Scherrer Institute (PSI) is a member of the Generation IV International Forum (GIF). In the past, the research at PSI focused mainly on HTR, SFR, and GFR. Currently, a research program was established also for Molten Salt Reactors (MSR). Safety is the key point and main interest of the MSR research at the Nuclear Energy and Safety (NES) department of PSI. However, it cannot be evaluated without knowing the system design, fuel chemistry, salt thermal-hydraulics features, safety and fuel cycle approach, and the relevant material and chemical limits. Accordingly, sufficient knowledge should be acquired in the other individual fields before the safety can be evaluated. The MSR research at NES may be divided into four working packages (WP): WP1: MSR core design and fuel cycle, WP2: MSR fuel behavior at nominal and accidental conditions, WP3: MSR thermal-hydraulics and decay heat removal system, WP4: MSR safety, fuel stream, and relevant limits. The WPs are proposed so that there are research topics which can be independently studied within each of them. The work plan of the four WPs is based on several ongoing or past national and international projects relevant to MSR, where NES/PSI participates. At the current stage, the program focuses on several specific and design independent studies. The safety is the key point and main long-term interest of the MSR research at NES. (author)

  18. Actuation method of molten carbonate fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Yasuhiko; Kimoto, Mamoru; Murakami, Shuzo; Furukawa, Nobuhiro

    1987-10-17

    A molten carbonate fuel cell uses reformed gas of crude fuel as fuel gas, but in this gas, CO/sub 2/ is contained in addition to H/sub 2/ and CO which participate the reaction in its fuel electrode. In order to make the reaction of the cell by these gases smoothly, CO/sub 2/ in the exhaust gas from the fuel electrode must be introduced efficiently to its oxygen electrode, however since unreacted H/sub 2/ and CO are contained in the above exhaust gas, they are oxidated and burned once in a boiler and transformed into H/sub 2/O (steam) and CO/sub 2/, then CO/sub 2/ generated in the fuel electrode is added thereto, and afterwards these gases with the air are introduced into the oxygen electrode. However, since this method hinders the high power generation efficiency, in this invention, the exhaust gas from the fuel electrode which burns the reformed gas is introduced into separation chambers separated with CO/sub 2/ permselective membranes, and the mixture of CO/sub 2/ in the above exhaust gas separated with the aforementioned permeable membranes and the air is supplied to the oxygen electrode. At the same time, H/sub 2/ and CO in the above exhaust gas which were not separated with the above permeable membranes are recirculated to the above fuel electrode. (3 figs)

  19. Molten fuel behaviour during slow overpower transients

    International Nuclear Information System (INIS)

    Guerin, Y.; Boidron, M.

    1985-01-01

    In large commercial reactors as Super-Phenix, if we take into account all the uncertainties on the pins and on the core, it is no longer possible to guarantee the absence of fuel melting during incidental events such as slow overpower transients. We have then to explain what happens in the pins when fuel melting occurs and to demonstrate that a limited amount of molten fuel generates no risk of clad failure. For that purpose, we may use the results of a great number of experiments (about 40) that have been performed at C.E.A., most of them in thermal reactor, but some experiments have also been performed in Rapsodie, especially during the last run of this reactor. In a great part of these experiments, fuel melting occurred at beginning of life, but we have also some results at different burnups up to 5 at %. It is not the aim of this paper to describe all these experiments and the results of their post irradiation examination, but to summarize the main conclusions that have been set out of them and that have enabled us to determine the main characteristics of fuel element behaviour when fuel melting occurs

  20. Thermally-assisted Magma Emplacement Explains Restless Calderas.

    Science.gov (United States)

    Amoruso, Antonella; Crescentini, Luca; D'Antonio, Massimo; Acocella, Valerio

    2017-08-11

    Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei caldera, Italy. Campi Flegrei experienced at least 4 major unrest episodes in the last decades. Our results indicate that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust. Our thermal models show that this repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth ~3 ka before the last eruption. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks. Our model of thermally-assisted unrest may have a wider applicability, possibly explaining also the dynamics of other restless calderas.

  1. Automatic Compound Annotation from Mass Spectrometry Data Using MAGMa.

    NARCIS (Netherlands)

    Ridder, L.O.; Hooft, van der J.J.J.; Verhoeven, S.

    2014-01-01

    The MAGMa software for automatic annotation of mass spectrometry based fragmentation data was applied to 16 MS/MS datasets of the CASMI 2013 contest. Eight solutions were submitted in category 1 (molecular formula assignments) and twelve in category 2 (molecular structure assignment). The MS/MS

  2. Loki Patera as the Surface of a Magma Sea

    Science.gov (United States)

    Matson, D. L.; Davies, A. G.; Veeder, G. J.; Rathbun, J. A.; Johnson, T. V.

    2004-01-01

    Inspired by the finding of Schubert et al that Io's figure is consistent with a hydrostatic shape, we explore the consequences of modeling Loki Patera as the surface of a large magma sea. This model is attractive because of its sheer simplicity and its usefulness in interpreting and predicting observations. Here, we report on that work.

  3. Shallow magma diversions during explosive diatreme-forming eruptions.

    Science.gov (United States)

    Le Corvec, Nicolas; Muirhead, James D; White, James D L

    2018-04-13

    The diversion of magma is an important mechanism that may lead to the relocation of a volcanic vent. Magma diversion is known to occur during explosive volcanic eruptions generating subterranean excavation and remobilization of country and volcanic rocks. However, feedbacks between explosive crater formation and intrusion processes have not been considered previously, despite their importance for understanding evolving hazards during volcanic eruptions. Here, we apply numerical modeling to test the impacts of excavation and subsequent infilling of diatreme structures on stress states and intrusion geometries during the formation of maar-diatreme complexes. Explosive excavation and infilling of diatremes affects local stress states which inhibits magma ascent and drives lateral diversion at various depths, which are expected to promote intra-diatreme explosions, host rock mixing, and vent migration. Our models demonstrate novel mechanisms explaining the generation of saucer-shaped sills, linked with magma diversion and enhanced intra-diatreme explosive fragmentation during maar-diatreme volcanism. Similar mechanisms will occur at other volcanic vents producing crater-forming eruptions.

  4. 75 FR 28778 - Magma Flood Retarding Structure (FRS) Supplemental Watershed Plan, Pinal County, AZ

    Science.gov (United States)

    2010-05-24

    ... DEPARTMENT OF AGRICULTURE Natural Resources Conservation Service Magma Flood Retarding Structure... statement is not being prepared for the Magma Flood Retarding Structure (FRS) Supplemental Watershed Plan... rehabilitate the Magma FRS to provide for continued flood protection for a portion of the Town of Florence and...

  5. Extensive, water-rich magma reservoir beneath southern Montserrat

    Science.gov (United States)

    Edmonds, M.; Kohn, S. C.; Hauri, E. H.; Humphreys, M. C. S.; Cassidy, M.

    2016-05-01

    South Soufrière Hills and Soufrière Hills volcanoes are 2 km apart at the southern end of the island of Montserrat, West Indies. Their magmas are distinct geochemically, despite these volcanoes having been active contemporaneously at 131-129 ka. We use the water content of pyroxenes and melt inclusion data to reconstruct the bulk water contents of magmas and their depth of storage prior to eruption. Pyroxenes contain up to 281 ppm H2O, with significant variability between crystals and from core to rim in individual crystals. The Al content of the enstatites from Soufrière Hills Volcano (SHV) is used to constrain melt-pyroxene partitioning for H2O. The SHV enstatite cores record melt water contents of 6-9 wt%. Pyroxene and melt inclusion water concentration pairs from South Soufriere Hills basalts independently constrain pyroxene-melt partitioning of water and produces a comparable range in melt water concentrations. Melt inclusions recorded in plagioclase and in pyroxene contain up to 6.3 wt% H2O. When combined with realistic melt CO2 contents, the depth of magma storage for both volcanoes ranges from 5 to 16 km. The data are consistent with a vertically protracted crystal mush in the upper crust beneath the southern part of Montserrat which contains heterogeneous bodies of eruptible magma. The high water contents of the magmas suggest that they contain a high proportion of exsolved fluids, which has implications for the rheology of the mush and timescales for mush reorganisation prior to eruption. A depletion in water in the outer 50-100 μm of a subset of pyroxenes from pumices from a Vulcanian explosion at Soufrière Hills in 2003 is consistent with diffusive loss of hydrogen during magma ascent over 5-13 h. These timescales are similar to the mean time periods between explosions in 1997 and in 2003, raising the possibility that the driving force for this repetitive explosive behaviour lies not in the shallow system, but in the deeper parts of a vertically

  6. Experimental studies on natural circulation in molten salt loops

    International Nuclear Information System (INIS)

    Srivastava, A.K.; Borgohain, A.; Maheshwari, N.K.; Vijayan, P.K.

    2015-01-01

    Molten salts are increasingly getting attention as a coolant and storage medium in solar thermal power plants and as a liquid fuel, blanket and coolant in Molten Salt Reactors (MSR’s). Two different test facilities named Molten Salt Natural Circulation Loop (MSNCL) and Molten Active Fluoride salt Loop (MAFL) have been setup for thermal hydraulics, instrument development and material related studies relevant to MSR and solar power plants. The working medium for MSNCL is a molten nitrate salt which is a mixture of NaNO 3 and KNO 3 in 60:40 ratio and proposed as one of the coolant option for molten salt based reactor and coolant as well as storage medium for solar thermal power application. On the other hand, the working medium for MAFL is a eutectic mixture of LiF and ThF 4 and proposed as a blanket salt for Indian Molten Salt Breeder Reactor (MSBR). Steady state natural circulation experiments at different power level have been performed in the MSNCL. Transient studies for startup of natural circulation, loss of heat sink, heater trip and step change in heater power have also been carried out in the same. A 1D code LeBENC, developed in-house to simulate the natural circulation characteristics in closed loops, has been validated with the experimental data obtained from MSNCL. Further, LeBENC has been used for Pretest analysis of MAFL. This paper deals with the description of both the loops and experimental studies carried out in MSNCL. Validation of LeBENC along with the pretest analysis of MAFL using the same are also reported in this paper. (author)

  7. Magma Reservoirs Feeding Giant Radiating Dike Swarms: Insights from Venus

    Science.gov (United States)

    Grosfils, E. B.; Ernst, R. E.

    2003-01-01

    Evidence of lateral dike propagation from shallow magma reservoirs is quite common on the terrestrial planets, and examination of the giant radiating dike swarm population on Venus continues to provide new insight into the way these complex magmatic systems form and evolve. For example, it is becoming clear that many swarms are an amalgamation of multiple discrete phases of dike intrusion. This is not surprising in and of itself, as on Earth there is clear evidence that formation of both magma reservoirs and individual giant radiating dikes often involves periodic magma injection. Similarly, giant radiating swarms on Earth can contain temporally discrete subswarms defined on the basis of geometry, crosscutting relationships, and geochemical or paleomagnetic signatures. The Venus data are important, however, because erosion, sedimentation, plate tectonic disruption, etc. on Earth have destroyed most giant radiating dike swarm's source regions, and thus we remain uncertain about the geometry and temporal evolution of the magma sources from which the dikes are fed. Are the reservoirs which feed the dikes large or small, and what are the implications for how the dikes themselves form? Does each subswarm originate from a single, periodically reactivated reservoir, or do subswarms emerge from multiple discrete geographic foci? If the latter, are these discrete foci located at the margins of a single large magma body, or do multiple smaller reservoirs define the character of the magmatic center as a whole? Similarly, does the locus of magmatic activity change with time, or are all the foci active simultaneously? Careful study of giant radiating dike swarms on Venus is yielding the data necessary to address these questions and constrain future modeling efforts. Here, using giant radiating dike swarms from the Nemesis Tessera (V14) and Carson (V43) quadrangles as examples, we illustrate some of the dike swarm focal region diversity observed on Venus and briefly explore some

  8. Seismic tremors and magma wagging during explosive volcanism.

    Science.gov (United States)

    Jellinek, A Mark; Bercovici, David

    2011-02-24

    Volcanic tremor is a ubiquitous feature of explosive eruptions. This oscillation persists for minutes to weeks and is characterized by a remarkably narrow band of frequencies from about 0.5 Hz to 7 Hz (refs 1-4). Before major eruptions, tremor can occur in concert with increased gas flux and related ground deformation. Volcanic tremor is thus of particular value for eruption forecasting. Most models for volcanic tremor rely on specific properties of the geometry, structure and constitution of volcanic conduits as well as the gas content of the erupting magma. Because neither the initial structure nor the evolution of the magma-conduit system will be the same from one volcano to the next, it is surprising that tremor characteristics are so consistent among different volcanoes. Indeed, this universality of tremor properties remains a major enigma. Here we employ the contemporary view that silicic magma rises in the conduit as a columnar plug surrounded by a highly vesicular annulus of sheared bubbles. We demonstrate that, for most geologically relevant conditions, the magma column will oscillate or 'wag' against the restoring 'gas-spring' force of the annulus at observed tremor frequencies. In contrast to previous models, the magma-wagging oscillation is relatively insensitive to the conduit structure and geometry, which explains the narrow band of tremor frequencies observed around the world. Moreover, the model predicts that as an eruption proceeds there will be an upward drift in both the maximum frequency and the total signal frequency bandwidth, the nature of which depends on the explosivity of the eruption, as is often observed.

  9. Mezcla de magmas en Vulcanello (Isla Vulcano, Italia

    Directory of Open Access Journals (Sweden)

    Aparicio, A.

    2008-06-01

    Full Text Available Volcanic activity in Vulcano starts about 350 ka ago and continues up to present day with the development of thre main episodes corresponding to the calderas of Piano and La Fossa, and Vulcanello. These cover a compositional range from rhyolitic to trachybasaltic rocks. This lithological diversity is produced by different petrogenetic processes such as fractional crystallization, assimilation coupled to fractional crystallization (AFC, mixing, etc.The eruption of Vulcanello area emitted trachyandesitic materials, including shoshonites and latites. A magma-mixing process is established between trachytes and shoshonites to origine latites. Trachytes and rhyolites are produced by fractional crystallization and by ACF processes (assimilation of sedimentary rocks from trachyandesitic magmas.La actividad volcánica de Isla Vulcano comienzó aproximadamente hace 350.000 años y continúa hasta la actualidad con el desarrollo de tres grandes episodios correspondientes a las caldera de Piano, caldera de Fossa y a Vulcanello, que han emitido piroclastos y coladas de composiciones muy variadas, desde riolitas a traquibasaltos. Esta variedad litológica ha sido relacionada con procesos petrogenéticos tan diversos como cristalización fraccionada, asimilación simultánea con cristalización (ACF, mezcla de magmas, etc.El episodio de Vulcanello emite rocas traquiandesíticas, con composiciones shoshoníticas y latíticas. Un proceso de mezcla de magmas es reconocido entre traquitas y shoshonitas para generar latitas. Traquitas y riolitas son producidas por procesos de cristalización fraccionada simple y por ACF con asimilación de rocas sedimentarias a partir de magmas traquiandesíticos.

  10. Evidence for many-body interactions in the structure of molten alkali chlorides

    International Nuclear Information System (INIS)

    Malescio, G.P.; Tosi, M.P.

    1985-02-01

    An inversion of the measured partial structure factors of molten sodium chloride is attempted in order to assess some qualitative features of interionic forces in the melt. We start from a calculation of liquid structure and thermodynamic properties by means of a refined theory based on interionic pair potentials determined from properties of the solid phase. This yields very good agreement with the measured values of the internal energy and the compressibility of the liquid, whereas discrepancies with the observed structure are mainly localized in the region of interionic distances outside the minimum of the cation-anion potential. These discrepancies, when interpreted in terms of effective pair potentials in the melt through inversion of the structural data, strongly suggest the presence of many-body effects, insofar as such effective pair potentials oscillate with the local liquid structure and are inconsistent with the measured thermodynamic quantities. A similar analysis of data on molten rubidium and cesium chloride, though harder to carry out quantitatively, supports the above conclusion. (author)

  11. Uranium (III)-Plutonium (III) co-precipitation in molten chloride

    Science.gov (United States)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2018-02-01

    Co-management of the actinides in an integrated closed fuel cycle by a pyrochemical process is studied at the laboratory scale in France in the CEA-ATALANTE facility. In this context the co-precipitation of U(III) and Pu(III) by wet argon sparging in LiCl-CaCl2 (30-70 mol%) molten salt at 705 °C is studied. Pu(III) is prepared in situ in the molten salt by carbochlorination of PuO2 and U(III) is then introduced as UCl3 after chlorine purge by argon to avoid any oxidation of uranium up to U(VI) by Cl2. The oxide conversion yield through wet argon sparging is quantitative. However, the preferential oxidation of U(III) in comparison to Pu(III) is responsible for a successive conversion of the two actinides, giving a mixture of UO2 and PuO2 oxides. Surprisingly, the conversion of sole Pu(III) in the same conditions leads to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation of Pu(III) to Pu(IV). This is in contrast with coconversion of U(III)-Pu(III) mixtures but in agreement with the conversion of Ce(III).

  12. Magma-assisted strain localization in an orogen-parallel transcurrent shear zone of southern Brazil

    Science.gov (United States)

    Tommasi, AndréA.; Vauchez, Alain; Femandes, Luis A. D.; Porcher, Carla C.

    1994-04-01

    In a lithospheric-scale, orogen-parallel transcurrent shear zone of the Pan-African Dom Feliciano belt of southern Brazil, two successive generations of magmas, an early calc-alkaline and a late peraluminous, have been emplaced during deformation. Microstructures show that these granitoids experienced a progressive deformation from magmatic to solid state under decreasing temperature conditions. Magmatic deformation is indicated by the coexistence of aligned K-feldspar, plagioclase, micas, and/or tourmaline with undeformed quartz. Submagmatic deformation is characterized by strain features, such as fractures, lattice bending, or replacement reactions affecting only the early crystallized phases. High-temperature solid-state deformation is characterized by extensive grain boundary migration in quartz, myrmekitic K-feldspar replacement, and dynamic recrystallization of both K-feldspar and plagioclase. Decreasing temperature during solid-state deformation is inferred from changes in quartz crystallographic fabrics, decrease in grain size of recrystallized feldspars, and lower Ti amount in recrystallized biotites. Final low-temperature deformation is characterized by feldspar replacement by micas. The geochemical evolution of the synkinematic magmatism, from calc-alkaline metaluminous granodiorites with intermediate 87Sr/86Sr initial ratio to peraluminous granites with very high 87Sr/86Sr initial ratio, suggests an early lower crustal source or a mixed mantle/crustal source, followed by a middle to upper crustal source for the melts. Shearing in lithospheric faults may induce partial melting in the lower crust by shear heating in the upper mantle, but, whatever the process initiating partial melting, lithospheric transcurrent shear zones may collect melt at different depths. Because they enhance the vertical permeability of the crust, these zones may then act as heat conductors (by advection), promoting an upward propagation of partial melting in the crust

  13. Mafic-silicic magma interaction in the layered 1.87 Ga Soukkio Complex in Mäntsälä, southern Finland

    Directory of Open Access Journals (Sweden)

    Toni T. Eerola

    2002-01-01

    Full Text Available The Svecofennian layered Soukkio Complex (1.87 Ga in Mäntsälä, southern Finland, consists of layered tholeiitic gabbro and porphyritic calc-alkaline monzonite, quartz monzonite and granite, mingled together. The gabbro belongs to a group of ten mafic-ultramafic intrusions of Mäntsälä, part of the 150 km long and 20 km wide, linear, E-W trending Hyvinkää–Mäntsälä Gabbroic Belt(HMGB, representing syn-collisional magmatism. Structures and textures related to magma mingling and mixing occur in a 1–2 km wide zone around Lake Kilpijärvi, located at the center of the Soukkio Complex. The complex is compositionally stratified and consists of four zones:its base, found at the Western Zone, is a dynamically layered gabbro. The followingtonalite is probably a result of magma mixing. Felsic amoeboid layers and pipes, alternating with or cutting the fine-grained gabbro in the Central-Western Zone, resemble those of mafic-silicic layered intrusions in general. Mafic magmatic enclaves (MMEs and pillows form the South-Central Zone and disrupted synplutonic mafic dykes or sheets intruded the granite in the Eastern Zone. The MMEs and disrupted synplutonic mafic dykes or sheets show cuspate and chilled margins against the felsic host, quartz ocelli, corroded K-feldspar xenocrysts with or without plagioclase mantles, and acicular apatite, all typical features of magma mingling and mixing. Mixing is suggested by intermediate composition of MMEs between granitoid and gabbro, as well as by their partly linear trends in some Harker diagrams. REE composition of the MMEs is similar to that of the Soukkio Gabbro, as expected for granite hosted MMEs. The model proposed for evolution of the Soukkio Complex involves intrusion of mafic magma into the crust, causing its partial melting. This generated granitic magma above the mafic chamber. Injections of mafic magma invaded the felsic chamber and those magmas interacted mainly by intermingling. Mingling and

  14. A Thermodynamic Approach for Modeling H2O-CO2 Solubility in Alkali-rich Mafic Magmas at Mid-crustal Pressures

    Science.gov (United States)

    Allison, C. M.; Roggensack, K.; Clarke, A. B.

    2017-12-01

    Volatile solubility in magmas is dependent on several factors, including composition and pressure. Mafic (basaltic) magmas with high concentrations of alkali elements (Na and K) are capable of dissolving larger quantities of H2O and CO2 than low-alkali basalt. The exsolution of abundant gases dissolved in alkali-rich mafic magmas can contribute to large explosive eruptions. Existing volatile solubility models for alkali-rich mafic magmas are well calibrated below 200 MPa, but at greater pressures the experimental data is sparse. To allow for accurate interpretation of mafic magmatic systems at higher pressures, we conducted a set of mixed H2O-CO2 volatile solubility experiments between 400 and 600 MPa at 1200 °C in six mafic compositions with variable alkali contents. Compositions include magmas from volcanoes in Italy, Antarctica, and Arizona. Results from our experiments indicate that existing volatile solubility models for alkali-rich mafic magmas, if extrapolated beyond their calibrated range, over-predict CO2 solubility at mid-crustal pressures. Physically, these results suggest that volatile exsolution can occur at deeper levels than what can be resolved from the lower-pressure experimental data. Existing thermodynamic models used to calculate volatile solubility at different pressures require two experimentally derived parameters. These parameters represent the partial molar volume of the condensed volatile species in the melt and its equilibrium constant, both calculated at a standard temperature and pressure. We derived these parameters for each studied composition and the corresponding thermodynamic model shows good agreement with the CO2 solubility data of the experiments. A general alkali basalt solubility model was also constructed by establishing a relationship between magma composition and the thermodynamic parameters. We utilize cation fractions from our six compositions along with four compositions from the experimental literature in a linear

  15. LIFE Materails: Molten-Salt Fuels Volume 8

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R; Brown, N; Caro, A; Farmer, J; Halsey, W; Kaufman, L; Kramer, K; Latkowski, J; Powers, J; Shaw, H; Turchi, P

    2008-12-11

    The goals of the Laser Inertial Fusion Fission Energy (LIFE) is to use fusion neutrons to fission materials with no enrichment and minimum processing and have greatly reduced wastes that are not of interest to making weapons. Fusion yields expected to be achieved in NIF a few times per day are called for with a high reliable shot rate of about 15 per second. We have found that the version of LIFE using TRISO fuel discussed in other volumes of this series can be modified by replacing the molten-flibe-cooled TRISO fuel zone with a molten salt in which the same actinides present in the TRISO particles are dissolved in the molten salt. Molten salts have the advantage that they are not subject to radiation damage, and hence overcome the radiation damage effects that may limit the lifetime of solid fuels such as TRISO-containing pebbles. This molten salt is pumped through the LIFE blanket, out to a heat exchanger and back into the blanket. To mitigate corrosion, steel structures in contact with the molten salt would be plated with tungsten or nickel. The salt will be processed during operation to remove certain fission products (volatile and noble and semi-noble fission products), impurities and corrosion products. In this way neutron absorbers (fission products) are removed and neutronics performance of the molten salt is somewhat better than that of the TRISO fuel case owing to the reduced parasitic absorption. In addition, the production of Pu and rare-earth elements (REE) causes these elements to build up in the salt, and leads to a requirement for a process to remove the REE during operation to insure that the solubility of a mixed (Pu,REE)F3 solid solution is not exceeded anywhere in the molten salt system. Removal of the REE will further enhance the neutronics performance. With molten salt fuels, the plant would need to be safeguarded because materials of interest for weapons are produced and could potentially be removed.

  16. LIFE Materails: Molten-Salt Fuels Volume 8

    International Nuclear Information System (INIS)

    Moir, R.; Brown, N.; Caro, A.; Farmer, J.; Halsey, W.; Kaufman, L.; Kramer, K.; Latkowski, J.; Powers, J.; Shaw, H.; Turchi, P.

    2008-01-01

    The goals of the Laser Inertial Fusion Fission Energy (LIFE) is to use fusion neutrons to fission materials with no enrichment and minimum processing and have greatly reduced wastes that are not of interest to making weapons. Fusion yields expected to be achieved in NIF a few times per day are called for with a high reliable shot rate of about 15 per second. We have found that the version of LIFE using TRISO fuel discussed in other volumes of this series can be modified by replacing the molten-flibe-cooled TRISO fuel zone with a molten salt in which the same actinides present in the TRISO particles are dissolved in the molten salt. Molten salts have the advantage that they are not subject to radiation damage, and hence overcome the radiation damage effects that may limit the lifetime of solid fuels such as TRISO-containing pebbles. This molten salt is pumped through the LIFE blanket, out to a heat exchanger and back into the blanket. To mitigate corrosion, steel structures in contact with the molten salt would be plated with tungsten or nickel. The salt will be processed during operation to remove certain fission products (volatile and noble and semi-noble fission products), impurities and corrosion products. In this way neutron absorbers (fission products) are removed and neutronics performance of the molten salt is somewhat better than that of the TRISO fuel case owing to the reduced parasitic absorption. In addition, the production of Pu and rare-earth elements (REE) causes these elements to build up in the salt, and leads to a requirement for a process to remove the REE during operation to insure that the solubility of a mixed (Pu,REE)F3 solid solution is not exceeded anywhere in the molten salt system. Removal of the REE will further enhance the neutronics performance. With molten salt fuels, the plant would need to be safeguarded because materials of interest for weapons are produced and could potentially be removed.

  17. Fundamental experiment on simulated molten core/concrete interaction

    International Nuclear Information System (INIS)

    Toda, S.; Katsumura, Y.

    1994-01-01

    If a complete and prolonged failure of coolant flow were to occur in a LWR or FBR, fission product decay heat would cause the fuel to overheat. If no available action to cool the fuel were taken, it would eventually melt. Ibis could lead to slumping of the molten core material and to the failure of the reactor pressure vessel and deposition of these materials into the concrete reactor cavity. Consequently, the molten core could melt and decompose the concrete. Vigorous agitation of the molten core pool by concrete decomposition gases is expected to enhance the convective heat transfer process. Besides the decomposition gases, melting concrete (slag) generated under the molten core pool will be buoyed up, and will also affect the downward heat transfer. Though, in this way, the heat transfer process across the interface is complicated by the slag and the gases evolved from the decomposed concrete, it is very important to make its process clear for the safety evaluation of nuclear reactors. Therefore, in this study, fundamental experiments were performed using simulated materials to observe the behaviors of the hot pool, slag and gases at the interface. Moreover, from the experimental observation, a correlation without empirical constants was proposed to calculate the interface heat transfer. The heat transfer across the interface would depend on thermo-physical interactions between the pool, slag and concrete which are changed by their thermal properties and interface temperature and so on. For example, the molten concrete is miscible in molten oxidic core debris, but is immiscible in metallic core debris. If a contact temperature between the molten core pool and the concrete falls below the solidus of the pool, solidification of the pool will occur. In this study, the case of immiscible slag in the pool is treated and solidification of the pool does not occur. Thus, water, paraffin and air were selected as the simulated molten core pool, concrete, and decomposition

  18. Simulation of Molten Salt Reactor dynamics

    International Nuclear Information System (INIS)

    Krepel, J.; Rohde, U.; Grundmann, U.

    2005-01-01

    Dynamics of the Molten Salt Reactor - one of the 'Generation IV' concepts - was studied in this paper. The graphite-moderated channel type MSR was selected for the numerical simulation of the reactor with liquid fuel. The MSR dynamics is very specific because of two physical peculiarities of the liquid fueled reactor: the delayed neutrons precursors are drifted by the fuel flow and the fission energy is immediately released directly into the coolant. Presently, there are not many accessible numerical codes appropriate for the MSR simulation, therefore the DYN3D-MSR code was developed based on the FZR in-house code DYN3D. It allows calculating of full 3D transient neutronics in combination with parallel channel type thermal-hydraulics. By means of DYN3D-MSR, several transients typical for the liquid fuel system were analyzed. Those transients were initiated by reactivity insertion, by overcooling of fuel at the core inlet, by the fuel pump start-up or coast-down, or by the blockage of selected fuel channels. In these considered transients, the response of the MSR is characterized by the immediate change of the fuel temperature with changing power and fast negative temperature feedback to the power. The response through the graphite temperature is slower. Furthermore, for big MSR cores fueled with U233 the graphite feedback coefficient can be positive. In this case the addition of erbium to the graphite can ensure the inherent safety features. The DYN3D-MSR code has been shown to be an effective tool for MSR dynamics studies. (author)

  19. An assessment of the Th-Hf-Ta diagram as a discriminant for tectomagnetic classifications and in the detection of crustal contamination of magmas

    International Nuclear Information System (INIS)

    Thompson, R.N.; Morrison, M.A.; Mattey, D.P.; Dickin, A.P.; Moorbath, S.

    1980-01-01

    The Th-Hf-Ta diagram, recently proposed as a means of discriminating basalts erupted in various tectonic environments and of detecting crustal contamination in such magmas, is shown to be unsatisfactory for both of its stated purposes. Data are presented for Th, Hf, Ta, Sr and Sr- and Pb-isotopes in basic lavas and a dolerite sill from the ensialic British Tertiary Volcanic Province (BTVP). Taken in conjunction with published results, the isotopic ratios show that some of the BTVP basic magmas are essentially uncontaminated by continental crust, except for the selective introduction of small variable amounts of unradiogenic Pb. Those BTVP magmas which show appreciable isotopic contamination have interacted with either upper or lower crust, or both. Th/(Hf + Ta) is insensitive to contamination with the Th-poor lower crust of cratons but rises during gross contamination with Th-rich upper crust. BTVP basic magmas containing negligible to moderate crustal isotopic components plot in the field of the Th-Hf-Ta diagram occupied by normal mid-ocean ridge basalts. Other volcanic provinces of known tectonic setting which plot wholly or partially outside their appropriate fields on the Th-Hf-Ta diagram are: the Hawaii-Emperor Seamount Chain, the Snake River Plain (Idaho, U.S.A.), the Azores and the Gregory Rift (Kenya). (orig.)

  20. Development of High Temperature Transport System for Molten Salt

    International Nuclear Information System (INIS)

    Lee, S. H.; Lee, H. S.; Kim, J. G.

    2011-01-01

    Pyroprocessing technology is one of the the most promising technologies for the advanced fuel cycle with favorable economic potential and intrinsic proliferation-resistance. The electrorefining process, one of main processes which is composed of pyroprocess to recover the useful elements from spent fuel, is under development at the Korea Atomic Energy Research Institute as a sub process of the pyrochemical treatment of spent PWR fuel. High-temperature molten salt transport technologies are required because a molten salt should be transported from the electrorefiner to electrowiner after the electrorefining process. Therefore, in pyrometallurgical processing, the development of high-temperature molten salt transport technologies is a crucial prerequisite. However, there have been a few transport studies on high-temperature molten salt. In this study, an apparatus for suction transport experiments was designed and constructed for the development of high temperature transport technology for molten salt, and the performance test of the apparatus was performed. And also, predissolution test of the salt was carried out using the reactor with furnace in experimental apparatus

  1. Application of lithium in molten-salt reduction processes

    International Nuclear Information System (INIS)

    Gourishankar, K. V.

    1998-01-01

    Metallothermic reductions have been extensively studied in the field of extractive metallurgy. At Argonne National Laboratory (ANL), we have developed a molten-salt based reduction process using lithium. This process was originally developed to reduce actinide oxides present in spent nuclear fuel. Preliminary thermodynamic considerations indicate that this process has the potential to be adapted for the extraction of other metals. The reduction is carried out at 650 C in a molten-salt (LiCl) medium. Lithium oxide (Li 2 O), produced during the reduction of the actinide oxides, dissolves in the molten salt. At the end of the reduction step, the lithium is regenerated from the salt by an electrowinning process. The lithium and the salt from the electrowinning are then reused for reduction of the next batch of oxide fuel. The process cycle has been successfully demonstrated on an engineering scale in a specially designed pyroprocessing facility. This paper discusses the applicability of lithium in molten-salt reduction processes with specific reference to our process. Results are presented from our work on actinide oxides to highlight the role of lithium and its effect on process variables in these molten-salt based reduction processes

  2. Steam gasification of plant biomass using molten carbonate salts

    International Nuclear Information System (INIS)

    Hathaway, Brandon J.; Honda, Masanori; Kittelson, David B.; Davidson, Jane H.

    2013-01-01

    This paper explores the use of molten alkali-carbonate salts as a reaction and heat transfer medium for steam gasification of plant biomass with the objectives of enhanced heat transfer, faster kinetics, and increased thermal capacitance compared to gasification in an inert gas. The intended application is a solar process in which concentrated solar radiation is the sole source of heat to drive the endothermic production of synthesis gas. The benefits of gasification in a molten ternary blend of lithium, potassium, and sodium carbonate salts is demonstrated for cellulose, switchgrass, a blend of perennial plants, and corn stover through measurements of reaction rate and product composition in an electrically heated reactor. The feedstocks are gasified with steam at 1200 K in argon and in the molten salt. The use of molten salt increases the total useful syngas production by up to 25%, and increases the reactivity index by as much as 490%. Secondary products, in the form of condensable tar, are reduced by 77%. -- Highlights: ► The presence of molten salt increases the rate of gasification by up to 600%. ► Reaction rates across various feedstocks are more uniform with salt present. ► Useful syngas yield is increased by up to 30% when salt is present. ► Secondary production of liquid tars are reduced by 77% when salt is present.

  3. Natural convection heat transfer in the molten metal pool

    International Nuclear Information System (INIS)

    Park, R.J.; Kim, S.B.; Kim, H.D.; Choi, S.M.

    1997-01-01

    Analytical studies using the FLOW-3D computer program have been performed on natural convection heat transfer of a high density molten metal pool, in order to evaluate the coolability of the corium pool. The FLOW-3D results on the temperature distribution and the heat transfer rate in the molten metal pool region have been compared and evaluated with the experimental data. The FLOW-3D results have shown that the developed natural convection flow contributes to the solidified crust formation of the high density molten metal pool. The present FLOW-3D results, on the relationship between the Nusselt number and the Rayleigh number in the molten metal pool region, are more similar to the calculated results of Globe and Dropkin's correlation than any others. The natural convection heat transfer in the low aspect ratio case is more substantial than that in the high aspect ratio case. The FLOW-3D results, on the temperature profile and on the heat transfer rate in the molten metal pool region, are very similar to the experimental data. The heat transfer rate of the internal heat generation case is higher than that of the bottom heating case at the same heat supply condition. (author)

  4. Ground surface deformation patterns, magma supply, and magma storage at Okmok volcano, Alaska, from InSAR analysis: 1. Intereruption deformation, 1997–2008

    Science.gov (United States)

    Lu, Zhong; Dzurisin, Daniel; Biggs, Juliet; Wicks, Charles; McNutt, Steve

    2010-01-01

    Starting soon after the 1997 eruption at Okmok volcano and continuing until the start of the 2008 eruption, magma accumulated in a storage zone centered ~3.5 km beneath the caldera floor at a rate that varied with time. A Mogi-type point pressure source or finite sphere with a radius of 1 km provides an adequate fit to the deformation field portrayed in time-sequential interferometric synthetic aperture radar images. From the end of the 1997 eruption through summer 2004, magma storage increased by 3.2–4.5 × 107 m3, which corresponds to 75–85% of the magma volume erupted in 1997. Thereafter, the average magma supply rate decreased such that by 10 July 2008, 2 days before the start of the 2008 eruption, magma storage had increased by 3.7–5.2 × 107 m3 or 85–100% of the 1997 eruption volume. We propose that the supply rate decreased in response to the diminishing pressure gradient between the shallow storage zone and a deeper magma source region. Eventually the effects of continuing magma supply and vesiculation of stored magma caused a critical pressure threshold to be exceeded, triggering the 2008 eruption. A similar pattern of initially rapid inflation followed by oscillatory but generally slowing inflation was observed prior to the 1997 eruption. In both cases, withdrawal of magma during the eruptions depressurized the shallow storage zone, causing significant volcano-wide subsidence and initiating a new intereruption deformation cycle.

  5. Pressure effect on Fe3+/FeT in silicate melts and applications to magma redox, particularly in magma oceans

    Science.gov (United States)

    Zhang, H.; Hirschmann, M. M.

    2014-12-01

    The proportions of Fe3+ and Fe2+ in magmas reflect the redox conditions of their origin and influence the chemical and physical properties of natural silicate liquids, but the relationship between Fe3+/FeT and oxygen fugacity depends on pressure owing to different molar volumes and compressibilities of Fe3+ and Fe2+ in silicates. An important case where the effect of pressure effect may be important is in magma oceans, where well mixed (and therefore potentially uniform Fe3+/FeT) experiencses a wide range of pressures, and therefore can impart different ƒO2 at different depths, influencing magma ocean degassing and early atmospheres, as well as chemical gradients within magma oceans. To investigate the effect of pressure on magmatic Fe3+/FeT we conducted high pressure expeirments on ƒO2-buffered andestic liquids. Quenched glasses were analyzed by Mössbauer spectroscopy. To verify the accuracy of Mössbauer determinations of Fe3+/FeT in glasses, we also conducted low temperature Mössbauer studies to determine differences in the recoilless fraction (ƒ) of Fe2+ and Fe3. These indicate that room temperature Mössbauer determinations of on Fe3+/FeT glasses are systematically high by 4% compared to recoilless-fraction corrected ratios. Up to 7 GPa, pressure decreases Fe3+/FeT, at fixed ƒO2 relative to metal-oxide buffers, meaning that an isochemical magma will become more reduced with decreasing pressure. Consequently, for small planetary bodies such as the Moon or Mercury, atmospheres overlying their MO will be highly reducing, consisting chiefly of H2 and CO. The same may also be true for Mars. The trend may reverse at higher pressure, as is the case for solid peridotite, and so for Earth, Venus, and possibly Mars, more oxidized atmospheres above MO are possible. Diamond anvil experiments are underway to examine this hypothesis.

  6. The expected greenhouse benefits from developing magma power at Long Valley, California

    International Nuclear Information System (INIS)

    Haraden, John.

    1995-01-01

    Magma power is the production of electricity from shallow magma bodies. Before magma becomes a practical source of power, many engineering problems must still be solved. When they are solved, the most likely site for the first magma power plant is Long Valley, California, USA. In this paper, we examine the greenhouse benefits from developing Long Valley. By generating magma power and by curtailing an equal amount of fossil power, we estimate the expected mass and the expected discounted value of reduced CO 2 emissions. For both measures, the expected benefits seem to be substantial. (author)

  7. A Microsoft Excel interface for rhyolite-MELTS: a tool for research and teaching of magma properties and evolution

    Science.gov (United States)

    Gualda, G. A.; Ghiorso, M. S.

    2013-12-01

    The thermodynamic modeling software MELTS (and its derivatives) is a powerful and much utilized tool for investigating crystallization and melting in natural magmatic systems. Rhyolite-MELTS (Gualda et al. 2012, J. Petrol. 53:875-890) is a recent recalibration of MELTS aimed at better capturing the evolution of magmas present in the upper crust (up to ~400 MPa pressure). Currently, most users of rhyolite-MELTS rely on a graphical user interface (GUI), which can be run on UNIX/LINUX and Mac OS X computers. While the interface is powerful and flexible, it can be somewhat cumbersome for the novice and the output is in the form of text files that need to be processed offline. This situation is probably the main reason why MELTS - despite great potential - has not been used more frequently for teaching purposes. We are currently developing an alternative GUI for rhyolite-MELTS using web services consumed by a VBA backend in Microsoft Excel©. The goal is to create a much more interactive tool, that is easy to use that can be made available to a widespread audience, and that will be useful for both research and teaching. The interface is contained within a macro-enabled workbook, which includes editable cells where the user can insert the model input information. Interface buttons initiate computations that are executed on a central server at OFM Research in Seattle (WA). Results of simple calculations are shown immediately within the interface itself. For instance, a user can very rapidly determine the temperature at which a magma of a given composition is completely molten (i.e. find the liquidus); or determine which phases are present, in what abundances, their compositions, and their physical properties (e.g. density, viscosity) at any given combination of temperature, pressure and oxygen fugacity. We expect that using the interface in this mode will greatly facilitate building intuition about magmas and their properties. It is also possible to combine a sequence of

  8. The origin and evolution of silicic magmas during continental rifting: new constraints from trace elements and oxygen isotopes from Ethiopian volcanoes

    Science.gov (United States)

    Hutchison, W.; Boyce, A.; Mather, T. A.; Pyle, D. M.; Yirgu, G.; Gleeson, M. L.

    2017-12-01

    The petrologic diversity of rift magmas is generated by two key processes: interaction with the crust via partial melting or assimilation; and closed-system fractional crystallization of the parental magma. It is not yet known whether these two petrogenetic processes vary spatially between different rift settings, and whether there are any significant secular variations during rift evolution. The Ethiopian Rift is the ideal setting to test these hypotheses because it captures the transition from continental rifting to sea-floor spreading and has witnessed the eruption of large volumes of mafic and silicic volcanic rocks since 30 Ma. We use new oxygen isotope (δ18O) and trace element data to fingerprint fractional crystallisation and partial crustal melting processes in Ethiopia and evaluate spatial variations between three active rift segments. δ18O measurements are used to examine partial crustal melting processes. We find that most δ18O data from basalts to rhyolites fall within the bounds of modelled fractional crystallization trajectories (i.e., 5.5-6.5 ‰). Few samples deviate from this trend, emphasising that fractional crystallization is the dominant petrogenetic processes and that little fusible Precambrian crustal material (δ18O of 7-18 ‰) remain to be assimilated beneath the magmatic segments. Trace element systematics (e.g., Ba, Sr, Rb, Th and Zr) further underscore the dominant role of fractional crystallization but also reveal important variations in the degree of melt evolution between the volcanic systems. We find that the most evolved silicic magmas, i.e., those with greatest peralkalinity (molar Na2O+K2O>Al2O3), are promoted in regions of lowest magma flux off-axis and along rift. Our findings provide new information on the nature of the crust beneath Ethiopia's active magmatic segments and also have relevance for understanding ancient rift zones and the geotectonic settings that promote genesis of economically-valuable mineral deposits.

  9. Tube pumices as strain markers of the ductile-brittle transition during magma fragmentation

    Science.gov (United States)

    Martí, J.; Soriano, C.; Dingwell, D. B.

    1999-12-01

    Magma fragmentation-the process by which relatively slow-moving magma transforms into a violent gas flow carrying fragments of magma-is the defining feature of explosive volcanism. Yet of all the processes involved in explosively erupting systems, fragmentation is possibly the least understood. Several theoretical and laboratory studies on magma degassing and fragmentation have produced a general picture of the sequence of events leading to the fragmentation of silicic magma. But there remains a debate over whether magma fragmentation is a consequence of the textural evolution of magma to a foamed state where disintegration of walls separating bubbles becomes inevitable due to a foam-collapse criterion, or whether magma is fragmented purely by stresses that exceed its tensile strength. Here we show that tube pumice-where extreme bubble elongation is observed-is a well-preserved magmatic `strain marker' of the stress state immediately before and during fragmentation. Structural elements in the pumice record the evolution of the magma's mechanical response from viscous behaviour (foaming and foam elongation) through the plastic or viscoelastic stage, and finally to brittle behaviour. These observations directly support the hypothesis that fragmentation occurs when magma undergoes a ductile-brittle transition and stresses exceed the magma's tensile strength.

  10. When Magma Meets Carbonate: Explosive Criminals of Climate Change?

    Science.gov (United States)

    Carter, L. B.

    2017-12-01

    The natural carbon cycle is a key component of global climate change. Identifying and quantifying all processes in the cycle is essential to determine the effects of human greenhouse gas contributions and make future predictions. Volcanoes are the main natural source of carbon dioxide to the atmosphere [1]. In settings where carbonate rocks underlie the edifice, they can be consumed by magma passing through, which can release extra CO2, potentially explaining the extremely high emissions at Mount Etna in Italy [2-4]. We conduct laboratory experiments, mimicking conditions in the crust, to study how different carbonate rocks interact with hot magmas at pressure, and determine the amount of CO2 generated. We find that some types of magma can raise volcanic gas output and cause more explosive and dangerous eruptions [5-6]. Others are more likely to release hot fluids to the surrounding rocks, releasing CO2 by skarnification, which leaves economically important ores like in the western US [3,7] but can weaken the subsurface, potentially leading to landslides. Gas can also be released on the flanks of a volcano or in regions lacking an active volcano, due to the breakdown of certain carbonate rocks by heat [7], seen as bubbling springs in Yellowstone [8]. Our experiments indicate that if dolostone, not limestone, surrounds a magma chamber, over half the CO2 that was locked in the crust can escape even at lower temperatures a distance away. These processes are perhaps pertinent to why the Earth's climate was warm >50 million years ago, when more magma-carbonate interaction likely occurred than today [3] and thus contributed several times the current volcanic output [4] to the atmosphere. As significant parts of the long-term carbon cycle, it is necessary to include magma-carbonate reactions when considering climate changes before taking into account human input. [1] Aiuppa et al 2017 ESciRev (168) 24-47; [2] Ganino and Arndt 2009 Geol (37) 323-326; [3] Lee et al. 2013

  11. The Solubility of metal oxides in molten carbonates - why the acid-basic chemistry fails?

    DEFF Research Database (Denmark)

    Bjerrum, Niels; Qingfeng, Li; Borup, Flemming

    1999-01-01

    Solubilities of various metal oxides in molten Li/K carbonates have been measured at 650°C under carbon dioxide atmosphere. It is found that the solubility of NiO and PbO decreases with increasing lithium mole fraction and decreasing CO2 partial pressure. On the other hand, the emf measurement...... shows opposite effects, i.e., decreasing CO2 pressure leads to more negative emf values but increasing lithium content gives more positive emf values. This contradiction is explained by means of a complex formation model. The possible species for lead are proposed to be [Pb(CO3)2]-2 and/or [Pb(CO3) 3...

  12. New rational nuclear energy system composed of accelerator molten-salt breeder (AMSB) and molten-salt power stations (MSCR)

    International Nuclear Information System (INIS)

    Furukawa, K.

    1985-01-01

    For the next century, it was predicted that some rational fission energy system breeding in significantly short doubling time less than 10 years should be developed replacing the fossil fuels. In practice, this rationality, that is, simplicity and high economy could be realized by the natural combination of: molten salt fuel concept; accelerator (spallation) breeding concept; and Thorium fuel cycle concept, in the symbiont system of Accelerator Molten-Salt breeders and Molten-Salt Power Stations. The economy of this system might significantly become better than the other breeder systems, although the prediction in Chapter 6 was too much conservative. Its more important aspect is the low cost of future R and D, which depend on the rational character of Molten-Fluoride Technology and really is verified by the basic R and D cost (only $0.13 B) in Oak Ridge N.L. It is interesting that molten-salt technology will be able to apply to chemical processing of U-Pu oxide fuels by the developing effort by USSR in near future. This fact and the demand of small power stations such as 150MWe MSCR presented here will be able to bridge between the present and the next century

  13. EFFECTS OF STELLAR FLUX ON TIDALLY LOCKED TERRESTRIAL PLANETS: DEGREE-1 MANTLE CONVECTION AND LOCAL MAGMA PONDS

    International Nuclear Information System (INIS)

    Gelman, S. E.; Elkins-Tanton, L. T.; Seager, S.

    2011-01-01

    We model the geodynamical evolution of super-Earth exoplanets in synchronous rotation about their star. While neglecting the effects of a potential atmosphere, we explore the parameter spaces of both the Rayleigh number and intensity of incoming stellar flux, and identify two main stages of mantle convection evolution. The first is a transient stage in which a lithospheric temperature and thickness dichotomy emerges between the substellar and the antistellar hemispheres, while the style of mantle convection is dictated by the Rayleigh number. The second stage is the development of degree-1 mantle convection. Depending on mantle properties, the timescale of onset of this second stage of mantle evolution varies from order 1 to 100 billion years of simulated planetary evolution. Planets with higher Rayleigh numbers (due to, for instance, larger planetary radii than the Earth) and planets whose incoming stellar flux is high (likely for most detectable exoplanets) will develop degree-1 mantle convection most quickly, on the order of 1 billion years, which is within the age of many planetary systems. Surface temperatures range from 220 K to 830 K, implying the possibility of liquid water in some regions near the surface. These results are discussed in the context of stable molten magma ponds on hotter planets, and the habitability of super-Earths which may lie outside the Habitable Zone.

  14. Electrochemical-metallothermic reduction of zirconium in molten salt solutions

    International Nuclear Information System (INIS)

    McLaughlin, D.F.; Talko, F.

    1990-01-01

    This patent describes a method for separating hafnium from zirconium of the type wherein a feed containing zirconium and hafnium chlorides is prepared from zirconium-hafnium chloride and the feed is introduced into a distillation column, which distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a hafnium chloride enriched stream is taken from the top of the column and a zirconium enriched chloride stream is taken from the bottom of the column. It comprises: reducing the zirconium enriched chloride stream taken from the distillation column to metal by electrochemically reducing an alkaline earth metal in a molten salt bath with the molten salt in the molten salt bath consisting essentially of a mixture of at least one alkali metal chloride and at least one alkaline earth metal chloride and zirconium chloride, with the reduced alkaline earth metal reacting with the zirconium chloride to produce zirconium metal and alkaline earth metal chloride

  15. Critical survey on electrode aging in molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, K.

    1979-12-01

    To evaluate potential electrodes for molten carbonate fuel cells, we reviewed the literature pertaining to these cells and interviewed investigators working in fuel cell technology. In this critical survey, the effect of three electrode aging processes - corrosion or oxidation, sintering, and poisoning - on these potential fuel-cell electrodes is presented. It is concluded that anodes of stabilized nickel and cathodes of lithium-doped NiO are the most promising electrode materials for molten carbonate fuel cells, but that further research and development of these electrodes are needed. In particular, the effect of contaminants such as H/sub 2/S and HCl on the nickel anode must be investigated, and methods to improve the physical strength and to increase the conductivity of NiO cathodes must be explored. Recommendations are given on areas of applied electrode research that should accelerate the commercialization of the molten carbonate fuel cell. 153 references.

  16. Propagating particle density fluctuations in molten NaCl

    International Nuclear Information System (INIS)

    Demmel, F.; Hosokawa, S.; Pilgrim, W.-C.; Lorenzen, M.

    2004-01-01

    In this paper we present the observation of acoustic modes in the spectra of molten NaCl measured over a large momentum transfer range using synchrotron radiation. A surprisingly large positive dispersion was deduced with a mode velocity exceeding the adiabatic value by nearly 70%. The large effect seems to be describable as a viscoelastic reaction of the liquid. Additionally, the derived dispersion resembles the Q-ω relation of the acoustic modes in liquid sodium. As an explanation for the large positive dispersion we propose that the density fluctuations in molten NaCl can be interpreted as a decoupled motion of the lighter and smaller cations on a nearly resting anionic background. These molten alkali halide measurements are the first experimental evidences for the so-called fast sound in a binary ionic liquid

  17. Workshop on large molten pool heat transfer summary and conclusions

    International Nuclear Information System (INIS)

    1994-01-01

    The CSNI Workshop on Large Molten Heat Transfer held at Grenoble (France) in March 1994 was organised by CSNI's Principal Working Group on the Confinement of Accidental Radioactive Releases (PWG4) with the cooperation of the Principal Working Group on Coolant System Behaviour (FWG2) and in collaboration with the Grenoble Nuclear Research Centre of the French Commissariat a l'Energie Atomique (CEA). Conclusions and recommendations are given for each of the five sessions of the workshops: Feasibility of in-vessel core debris cooling through external cooling of the vessel; Experiments on molten pool heat transfer; Calculational efforts on molten pool convection; Heat transfer to the surrounding water - experimental techniques; Future experiments and ex-vessel studies (open forum discussion)

  18. Behaviour of molten reactor fuels under accident conditions

    International Nuclear Information System (INIS)

    Xavier Swamikannu, A.; Mathews, C.K.

    1980-01-01

    The behaviour of molten reactor fuels under accident conditions has received considerable importance in recent times. The chemical processes that occur in the molten state among the fuel, the clad components and the concrete of the containment building under the conditions of a core melt down accident in oxide fuelled reactors have been reviewed with the purpose of identifying areas of developmental work required to be performed to assess and minimize the consequences of such an accident. This includes the computation and estimation of vapour pressure of various gaseous species over the fuel, the clad and the coolant, providing of sacrificial materials in the concrete in order to protect the containment building in order to prevent release of radioactive gases into the atmosphere and understanding the distribution and chemical state of fission products in the molten fuel in order to provide for the effective removal of their decay heats. (auth.)

  19. Deuterium retention in molten salt electrodeposition tungsten coatings

    International Nuclear Information System (INIS)

    Zhou, Hai-Shan; Xu, Yu-Ping; Sun, Ning-Bo; Zhang, Ying-Chun; Oya, Yasuhisa; Zhao, Ming-Zhong; Mao, Hong-Min; Ding, Fang; Liu, Feng; Luo, Guang-Nan

    2016-01-01

    Highlights: • We investigate D retention in electrodeposition W coatings. • W coatings are exposed to D plasmas in the EAST tokamak. • A cathodic current density dependence on D retention is found. • Electrodeposition W exhibits lower D retention than VPS-W. - Abstract: Molten salt electrodeposition is a promising technology to manufacture the first wall of a fusion reactor. Deuterium (D) retention behavior in molten salt electrodeposition tungsten (W) coatings has been investigated by D-plasma exposure in the EAST tokamak and D-ion implantation in an ion beam facility. Tokamak exposure experiments demonstrate that coatings prepared with lower current density exhibit less D retention and milder surface damage. Deuterium-ion implantation experiments indicate the D retention in the molten salt electrodeposition W is less than that in vacuum plasma spraying W and polycrystalline W.

  20. Basic studies for molten-salt reactor engineering in Japan

    International Nuclear Information System (INIS)

    Ishiguro, R.; Sugiyama, K.; Sakashita, H.

    1985-01-01

    A research project of nuclear engineering for the molten-salt reactor is underway which is supported by the Grant-in-Aid for Scientific Research of the Ministry of Education of Japan. At present, the major effort is devoted only to basic engineering problems because of the limited amount of the grant. The reporters introduce these and related studies that have been carrying out in Japanese universities. Discussions on the following four subjects are summerized in this report: a) Vapour explosion when hight temperature molten-salts are brought into direct contact with water. b) Measurements of exact thermophysical properties of molten-salt. c) Free convection heat transfer with uniform internal heat generation and a constant heating rate from the bottem. d) Stability of frozen salt film on the container surface. (author)

  1. Deuterium retention in molten salt electrodeposition tungsten coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hai-Shan [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Xu, Yu-Ping [Science Island Branch of Graduate School, University of Science and Technology of China, Hefei (China); Sun, Ning-Bo; Zhang, Ying-Chun [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing (China); Oya, Yasuhisa [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka (Japan); Zhao, Ming-Zhong [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Mao, Hong-Min [Science Island Branch of Graduate School, University of Science and Technology of China, Hefei (China); Ding, Fang; Liu, Feng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Luo, Guang-Nan, E-mail: gnluo@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Science Island Branch of Graduate School, University of Science and Technology of China, Hefei (China); Hefei Center for Physical Science and Technology, Hefei (China); Hefei Science Center of Chinese Academy of Science, Hefei (China)

    2016-12-15

    Highlights: • We investigate D retention in electrodeposition W coatings. • W coatings are exposed to D plasmas in the EAST tokamak. • A cathodic current density dependence on D retention is found. • Electrodeposition W exhibits lower D retention than VPS-W. - Abstract: Molten salt electrodeposition is a promising technology to manufacture the first wall of a fusion reactor. Deuterium (D) retention behavior in molten salt electrodeposition tungsten (W) coatings has been investigated by D-plasma exposure in the EAST tokamak and D-ion implantation in an ion beam facility. Tokamak exposure experiments demonstrate that coatings prepared with lower current density exhibit less D retention and milder surface damage. Deuterium-ion implantation experiments indicate the D retention in the molten salt electrodeposition W is less than that in vacuum plasma spraying W and polycrystalline W.

  2. Molten salt reactors. Synthesis of studies realized between 1973 and 1983. Chemistry file

    International Nuclear Information System (INIS)

    1983-03-01

    The chemistry of molten salt reactors was first acquired by foreign literature and developed by experimental studies. Salt preparation, analysis, chemical and electrochemical properties, interaction with metals or graphites and use of molten lead for direct cooling are examined. [fr

  3. Compatibility of AlN ceramics with molten lithium

    Energy Technology Data Exchange (ETDEWEB)

    Yoneoka, Toshiaki; Sakurai, Toshiharu; Sato, Toshihiko; Tanaka, Satoru [Tokyo Univ., Department of Quantum Engineering and Systems Science, Tokyo (Japan)

    2002-04-01

    AlN ceramics were a candidate for electrically insulating materials and facing materials against molten breeder in a nuclear fusion reactor. In the nuclear fusion reactor, interactions of various structural materials with solid and liquid breeder materials as well as coolant materials are important. Therefore, corrosion tests of AlN ceramics with molten lithium were performed. AlN specimens of six kinds, different in sintering additives and manufacturing method, were used. AlN specimens were immersed into molten lithium at 823 K. Duration for the compatibility tests was about 2.8 Ms (32 days). Specimens with sintering additive of Y{sub 2}O{sub 3} by about 5 mass% formed the network structure of oxide in the crystals of AlN. It was considered that the corrosion proceeded by reduction of the oxide network and the penetration of molten lithium through the reduced pass of this network. For specimens without sintering additive, Al{sub 2}O{sub 3} containing by about 1.3% in raw material was converted to fine oxynitride particles on grain boundary or dissolved in AlN crystals. After immersion into lithium, these specimens were found to be sound in shape but reduced in electrical resistivity. These degradation of the two types specimens were considered to be caused by the reduction of oxygen components. On the other hand, a specimen sintered using CaO as sintering additive was finally became appreciably high purity. This specimen showed good compatibility for molten lithium at least up to 823 K. It was concluded that the reduction of oxygen concentration in AlN materials was essential in order to improve the compatibility for molten lithium. (author)

  4. Magma transport and olivine crystallization depths in Kīlauea’s East Rift Zone inferred from experimentally rehomogenized melt inclusions

    Science.gov (United States)

    Tuohy, Robin M; Wallace, Paul J.; Loewen, Matthew W; Swanson, Don; Kent, Adam J R

    2016-01-01

    Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai‘i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n=10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n=38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea’s summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the

  5. Magma transport and olivine crystallization depths in Kīlauea's east rift zone inferred from experimentally rehomogenized melt inclusions

    Science.gov (United States)

    Tuohy, Robin M.; Wallace, Paul J.; Loewen, Matthew W.; Swanson, Donald A.; Kent, Adam J. R.

    2016-07-01

    Concentrations of H2O and CO2 in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO2 concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO2 is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To investigate this problem, we heated olivine from the 1959 Kīlauea Iki and 1960 Kapoho (Hawai'i) eruptions in a 1-atm furnace to temperatures above the melt inclusion trapping temperature to redissolve the CO2 in shrinkage bubbles. The measured CO2 concentrations of the experimentally rehomogenized inclusions (⩽590 ppm for Kīlauea Iki [n = 10]; ⩽880 ppm for Kapoho, with one inclusion at 1863 ppm [n = 38]) overlap with values for naturally quenched inclusions from the same samples, but experimentally rehomogenized inclusions have higher within-sample median CO2 values than naturally quenched inclusions, indicating at least partial dissolution of CO2 from the vapor bubble during heating. Comparison of our data with predictions from modeling of vapor bubble formation and published Raman data on the density of CO2 in the vapor bubbles suggests that 55-85% of the dissolved CO2 in the melt inclusions at the time of trapping was lost to post-entrapment shrinkage bubbles. Our results combined with the Raman data demonstrate that olivine from the early part of the Kīlauea Iki eruption crystallized at <6 km depth, with the majority of olivine in the 1-3 km depth range. These depths are consistent with the interpretation that the Kīlauea Iki magma was supplied from Kīlauea's summit magma reservoir (∼2-5 km depth). In contrast, olivine from Kapoho, which was the rift zone extension of the Kīlauea Iki eruption, crystallized over a much wider range of depths (∼1-16 km). The wider depth range requires magma transport during the Kapoho eruption from deep beneath the summit

  6. Contrasting sodic and mildly potassic magma differentiation lineages at The Pleaides volcanic complex, northern Victoria Land, Antarctica

    Science.gov (United States)

    Kim, J.; Park, J. W.; Lee, J.; Kyle, P. R.; Lee, M. J.

    2017-12-01

    The magma evolution of The Pleiades, a Quaternary alkaline volcanic complex in northern Victoria Land, Antarctica, is investigated using major and trace elements, and Sr, Nd and Pb isotopic data. The volcanic rocks can be subdivided into two distinct magmatic lineages based on petrography and whole-rock compositions: (1) a sodic silica-undersaturated alkaline lineage with abundant kaersutite phenocrysts, and (2) a mildly-potassic and mildly-alkaline, nearly silica-saturated lineage containing olivine but not kaersutite. The basanite and trachybasalt of both lineages exhibit similar degrees of negative K anomalies, moderately steep rare earth element patterns, and elevated trace element ratios such as Ce/Pb (> 20) and Nb/U (> 38), suggesting their primary magmas were generated by low degree (≤3%) of partial melting of amphibole and garnet-bearing mantle sources. The sodic lineage is characterized by elevated 206Pb/204Pb (>19.5) ratios and narrow ranges of 87Sr/86Sr (0.70313-0.70327) and 143Nd/144Nd (0.51289-0.51290) ratios consistent with a significant HIMU component typical of Neogene volcanic rocks in Antarctica. The mafic rocks of the potassic lineage have isotopic compositions similar to those of the sodic lineage, however the evolved lavas in the lineage have higher 87Sr/86Sr (> 0.7035) and lower 143Nd/144Nd (< 0.51285) and 206Pb/204Pb (< 19.3) ratios than the mafic rocks, suggesting significant amounts of crustal contamination. The pressure-temperature paths estimated by clinopyroxene-liquid thermobarometry are similar in each lineage. The mafic magmas were emplaced at Moho depths ( 1.2 GPa) and the evolved magmas pooled at middle-crustal depths ( 0.7 GPa). Mass-balance calculations based on whole-rock and mineral compositions show that kaersutite fractionation has played a major role in magma differentiation of the sodic lineage whereas the compositional variations of the potassic lineage can be ascribed to fractionation of a kaersutite-free mineral

  7. Beryllium research on FFHR molten salt blanket

    International Nuclear Information System (INIS)

    Terai, T.; Tanaka, S.; Sze, D.-K.

    2000-01-01

    Force-free helical reactor, FFHR, is a demo-relevant heliotron-type D-T fusion reactor based on the great amount of R and D results obtained in the LHD project. Since 1993, collaboration works have made great progress in design studies of FFHR with standing on the major advantage of current-less steady operation with no dangerous plasma disruptions. There are two types of reference designs, FFHR-1 and FFHR-2, where molten Flibe (LiF-BeF2) is utilized as tritium breeder and coolant. In this paper, we present the outline of FFHR blanket design and some related R and D topics focusing on Be utilization. Beryllium is used as a neutron multiplier in the design and Be pebbles are placed in the front part of the tritium breeding zone. In a Flibe blanket, HF (TF) generated due to nuclear transmutation will be a problem because of its corrosive property. Though nickel-based alloys are thought to be intact in such a corrosive environment, FFHR blanket design does not adopt the alloys because of their induced radioactivity. The present candidate materials for the structure are low-activated ferritic steel (JLF-1), V-4Cr-4Ti, etc. They are capable to be corroded by HF in the operation condition, and Be is expected to work as a reducing agent in the system as well. Whether Be pebbles placed in a Flibe flow can work well or not is a very important matter. From this point, Be solubility in Flibe, reaction rate of the Redox reaction with TF in the liquid and on the surface of Be pebbles under irradiation, flowing behavior of Flibe through a Be pebble bed, etc. should be investigated. In 1997, in order to establish more practical and new data bases for advanced design works, we started a collaboration work of R and D on blanket engineering, where the Be research above mentioned is included. Preliminary dipping-test of Be sheets and in-situ tritium release experiment from Flibe with Be sheets have got started. (orig.)

  8. The introduction of the safety of molten salt reactor

    International Nuclear Information System (INIS)

    Zuo Jiaxu; Zhang Chunming

    2011-01-01

    This paper introduces the generation TV Nuclear Energy Systems and molten salt reactor which is the only fluid fuel reactor in the Gen-TV. Safety features and attributes of MSR are described. The supply of fuel and the minimum of waste are described. The clean molten salt in the secondary heat transport system transfers the heat from the primary heat exchanger to a high-temperature Brayton cycle that converts the heat to electricity. With the Brayton cycle, the thermal efficiency of the system will be improved. Base on the MSR, the thorium-uranium fuel cycle is also introduced. (authors)

  9. Calculation of β-effective of a molten salt reactor

    International Nuclear Information System (INIS)

    Hirakawa, N.; Sakaba, H.

    1987-01-01

    A method to calculate the β eff of a molten salt reactor was developed taking the effect of the flow of the molten salt into account. The method was applied to the 1000MW MSR design made by ORNL. The change in β eff due to the change in the residence time outside of the core of the fuel salt and to the change in the flow velocity when the total amount of the fuel salt is kept constant were investigated. It was found that β eff was reduced to 47.9% of the value when the fuel salt is at rest for the present design. (author)

  10. Subcritical enhanced safety molten-salt reactor concept

    International Nuclear Information System (INIS)

    Alekseev, P.N.; Ignatiev, V.V.; Men'shikov, L.I.; Prusakov, V.N.; Ponomarev-Stepnoy, N.N.; Subbotin, S.A.; Krasnykh, A.K.; Rudenko, V.T.; Somov, L.N.

    1995-01-01

    The nuclear power and its fuel cycle safety requirements can be met in the main by providing nuclear power with subcritical molten salt reactors (SMSR) - 'burner' with an external neutron source. The utilized molten salt fuel is the decisive advantage of the SMSR over other burners. Fissile and fertile nuclides in the burner are solved in a liquid salt in the form of fluorides. This composition acts simultaneously as: a) fuel, b) coolant, c) medium for chemical partitioning and reprocessing. The effective way of reducing the external source power consists in the cascade neutron multiplication in the system of coupled reactors with suppressed feedback between them. (author)

  11. Metallic materials corrosion problems in molten salt reactors

    International Nuclear Information System (INIS)

    Chauvin, G.; Dixmier, J.; Jarny, P.

    1977-01-01

    The USA forecastings concerning the molten salt reactors are reviewed (mixtures of fluorides containing the fuel, operating between 560 and 700 0 C). Corrosion problems are important in these reactors. The effects of certain characteristic factors on corrosion are analyzed: humidity and metallic impurities in the salts, temperature gradients, speed of circulation of salts, tellurium from fission products, coupling. In the molten fluorides and experimental conditions, the materials with high Ni content are particularly corrosion resistant alloys (hastelloy N). The corrosion of this material is about 2.6 mg.cm -2 at 700 0 C [fr

  12. Study of an F center in molten KCl

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1984-01-15

    It is shown that a discretized version of Feynman's path integral provides a convenient tool for the numerical investigation of the properties of an electron solvated in molten KCl. The binding energy, the magnetic susceptibility, and the pair correlation functions are calculated. The local structure around the solute electron appears to be different from that of an F center in the solid. The Feynman path of the electron dissolved in molten KCl is highly localized thus justifying the F center model. The effect of varying the e/sup -/-K/sup +/ pseudopotential is also reported.

  13. Molten core debris-sodium interactions: M-Series experiments

    International Nuclear Information System (INIS)

    Sowa, E.S.; Gabor, J.D.; Pavlik, J.R.; Cassulo, J.C.; Cook, C.J.; Baker, L. Jr.

    1979-01-01

    Five new kilogram-scale experiments have been carried out. Four of the experiments simulated the situation where molten core debris flows from a breached reactor vessel into a dry reactor cavity and is followed by a flow of sodium (Ex-vessel case) and one experiment simulated the flow of core debris into an existing pool of sodium (In-vessel case). The core debris was closely simulated by a thermite reaction which produced a molten mixture of UO 2 , ZrO 2 , and stainless steel. There was efficient fragmentation of the debris in all experiments with no explosive interactions observed

  14. Molten carbonate fuel cell integral matrix tape and bubble barrier

    International Nuclear Information System (INIS)

    Reiser, C.A.; Maricle, D.L.

    1983-01-01

    A molten carbonate fuel cell matrix material is described made up of a matrix tape portion and a bubble barrier portion. The matrix tape portion comprises particles inert to molten carbonate electrolyte, ceramic particles and a polymeric binder, the matrix tape being flexible, pliable and having rubber-like compliance at room temperature. The bubble barrier is a solid material having fine porosity preferably being bonded to the matrix tape. In operation in a fuel cell, the polymer binder burns off leaving the matrix and bubble barrier providing superior sealing, stability and performance properties to the fuel cell stack

  15. Thermal conditions and functional requirements for molten fuel containment

    International Nuclear Information System (INIS)

    Kang, C.S.; Torri, A.

    1980-05-01

    This paper discusses the configuration and functional requirements for the molten fuel containment system (MFCS) in the GCFR demonstration plant design. Meltdown conditions following a loss of shutdown cooling (LOSC) accident were studied to define the core debris volume for a realistic meltdown case. Materials and thicknesses of the molten fuel container were defined. Stainless steel was chosen as the sacrificial material and magnesium oxide was chosen as the crucible material. Thermal conditions for an expected quasi-steady state were analyzed. Highlights of the functional requirements which directly affect the MFCS design are discussed

  16. High-frequency dynamics in a molten binary alloy

    International Nuclear Information System (INIS)

    Alvarez, M.; Bermejo, F.J.; Verkerk, P.; Roessli, B.

    1999-01-01

    The nature of the finite wavelength collective excitations in liquid binary mixtures composed of atoms of very different masses has been of interest for more than a decade. The most prominent fact is the high frequencies at which they appear, well above those expected for a continuation to large wave vector of hydrodynamic sound. To better understand the microscopic dynamics of such systems, an inelastic neutron scattering experiment was performed on the molten alloy Li 4 Pb. We present the high-frequency excitations of molten Li 4 Pb which indeed show features substantially deviating from those expected for the propagation of an acoustic mode. (authors)

  17. Compatibility tests between molten salts and metal materials (2)

    International Nuclear Information System (INIS)

    Shiina, Yasuaki

    2003-08-01

    Latent heat storage technology using molten salts can reduce temperature fluctuations of heat transfer fluid by latent heat for middle and high temperature regions. This enables us to operate several heat utilization systems in cascade connected to High Temperature Gas Cooled Reactors (HTGRs) from high to low temperature range by setting the latent heat storage system after a heat utilization system to reduce thermal load after the heat utilization systems. This latent heat technology is expected to be used for effective use of heat such as equalization of electric load between night and daytime. In the application of the latent heat technology, compatibility between molten salts and metal materials is very important because molten salts are corrosive, and heat transfer pipes and vessels will contact with the molten salts. It will be necessary to prevail the latent heat storage technique that normal metal materials can be used for the pipes and vessels. However, a few studies have been reported of compatibility between molten salts and metals in middle and high temperature ranges. In this study, four molten salts, range of the melting temperature from 490degC to 800degC, are selected and five metals, high temperature and corrosion resistance steels of Alloy600, HastelloyB2, HastelloyC276, SUS310S and pure Nickel are selected for the test with the consideration of metal composition. Test was performed in an electric furnace by setting the molten salts and the metals in melting pots in an atmosphere of nitrogen. Results revealed excellent corrosion resistance of pure Nickel and comparatively low corrosion resistance of nickel base alloys such as Alloy600 and Hastelloys against Li 2 CO 3 . Corrosion resistance of SUS310S was about same as nickel based alloys. Therefore, if some amount of corrosion is permitted, SUS310S would be one of the candidate alloys for structure materials. These results will be used as reference data to select metals in latent heat technology

  18. Fabrication of catalytic electrodes for molten carbonate fuel cells

    Science.gov (United States)

    Smith, James L.

    1988-01-01

    A porous layer of catalyst material suitable for use as an electrode in a molten carbonate fuel cell includes elongated pores substantially extending across the layer thickness. The catalyst layer is prepared by depositing particulate catalyst material into polymeric flocking on a substrate surface by a procedure such as tape casting. The loaded substrate is heated in a series of steps with rising temperatures to set the tape, thermally decompose the substrate with flocking and sinter bond the catalyst particles into a porous catalytic layer with elongated pores across its thickness. Employed as an electrode, the elongated pores provide distribution of reactant gas into contact with catalyst particles wetted by molten electrolyte.

  19. Degassing during magma ascent in the Mule Creek vent (USA)

    Science.gov (United States)

    Stasiuk, M.V.; Barclay, J.; Carroll, M.R.; Jaupart, Claude; Ratte, J.C.; Sparks, R.S.J.; Tait, S.R.

    1996-01-01

    The structures and textures of the rhyolite in the Mule Creek vent (New Mexico, USA) indicate mechanisms by which volatiles escape from silicic magma during eruption. The vent outcrop is a 300-m-high canyon wall comprising a section through the top of a feeder conduit, vent and the base of an extrusive lava dome. Field relations show that eruption began with an explosive phase and ended with lava extrusion. Analyses of glass inclusions in quartz phenocrysts from the lava indicate that the magma had a pre-eruptive dissolved water content of 2.5-3.0 wt% and, during eruption, the magma would have been water-saturated over the vertical extent of the present outcrop. However, the vesicularity of the rhyolite is substantially lower than that predicted from closed-system models of vesiculation under equilibrium conditions. At a given elevation in the vent, the volume fraction of primary vesicles in the rhyolite increases from zero close to the vent margin to values of 20-40 vol.% in the central part. In the centre the vesicularity increases upward from approximately 20 vol.% at 300 m below the canyon rim to approximately 40 vol.% at 200 m, above which it shows little increase. To account for the discrepancy between observed vesicularity and measured water content, we conclude that gas escaped during ascent, probably beginning at depths greater than exposed, by flow through the vesicular magma. Gas escape was most efficient near the vent margin, and we postulate that this is due both to the slow ascent of magma there, giving the most time for gas to escape, and to shear, favouring bubble coalescence. Such shear-related permeability in erupting magma is supported by the preserved distribution of textures and vesicularity in the rhyolite: Vesicles are flattened and overlapping near the dense margins and become progressively more isolated and less deformed toward the porous centre. Local zones have textures which suggest the coalescence of bubbles to form permeable

  20. Finite automata over magmas: models and some applications in Cryptography

    Directory of Open Access Journals (Sweden)

    Volodymyr V. Skobelev

    2018-05-01

    Full Text Available In the paper the families of finite semi-automata and reversible finite Mealy and Moore automata over finite magmas are defined and analyzed in detail. On the base of these models it is established that the set of finite quasigroups is the most acceptable subset of the set of finite magmas at resolving model problems in Cryptography, such as design of iterated hash functions and stream ciphers. Defined families of finite semi-automata and reversible finite automata over finite $T$-quasigroups are investigated in detail. It is established that in this case models time and space complexity for simulation of the functioning during one instant of automaton time can be much lower than in general case.

  1. A magma ocean and the Earth's internal water budget

    Science.gov (United States)

    Ahrens, Thomas J.

    1992-01-01

    There are lines of evidence which relate bounds on the primordial water content of the Earth's mantle to a magma ocean and the accompanying Earth accretion process. We assume initially (before a magma ocean could form) that as the Earth accreted, it grew from volatile- (H2O, CO2, NH3, CH4, SO2, plus noble) gas-rich planetesimals, which accreted to form an initial 'primitive accretion core' (PAC). The PAC retained the initial complement of planetesimal gaseous components. Shock wave experiments in which both solid, and more recently, the gaseous components of materials such as serpentine and the Murchison meteorite have demonstrated that planetesimal infall velocities of less than 0.5 km/sec, induce shock pressures of less than 0.5 GPa and result in virtually complete retention of planetary gases.

  2. Evidence of a global magma ocean in Io's interior.

    Science.gov (United States)

    Khurana, Krishan K; Jia, Xianzhe; Kivelson, Margaret G; Nimmo, Francis; Schubert, Gerald; Russell, Christopher T

    2011-06-03

    Extensive volcanism and high-temperature lavas hint at a global magma reservoir in Io, but no direct evidence has been available. We exploited Jupiter's rotating magnetic field as a sounding signal and show that the magnetometer data collected by the Galileo spacecraft near Io provide evidence of electromagnetic induction from a global conducting layer. We demonstrate that a completely solid mantle provides insufficient response to explain the magnetometer observations, but a global subsurface magma layer with a thickness of over 50 kilometers and a rock melt fraction of 20% or more is fully consistent with the observations. We also place a stronger upper limit of about 110 nanoteslas (surface equatorial field) on the dynamo dipolar field generated inside Io.

  3. Rapid Transient Deformation From a Shallow Magmatic Source at the Socorro Magma Body, NM, USA?

    Science.gov (United States)

    Newman, A. V.; Chamberlin, R. M.; Love, D. W.; Dixon, T. H.; La Femina, P.

    2004-12-01

    The Socorro Magma Body (SMB) lies within the central Rio Grande Rift (RGR) Valley and is one of the largest known magma bodies in the Earth's continental crust. Studies of local microseismicity and deep seismic soundings revealed an unusually strong reflector approximately 70 km wide at 19 km depth and identified it as a large active sill-like crustal magma intrusion. Using precision leveling (1912-80) and InSAR (1992-99), previous studies have found ˜2-4 mm/yr of averaged uplift centered near San Acacia, over the center of the reflector, and corresponding to about 107 m3 of annual growth from an inflating sill at 19 km depth. We performed two GPS campaigns over the SMB on nine bedrock sites in 2002 and 2003. Vertical GPS velocities from six sites forming a transect over the central SMB are between ˜10 and 20 mm (1σ ˜10 mm) with the maximum measured surface uplift at two central stations near San Acacia. However, three sites forming a partial transect ˜12 km north show no uplift for this period. Additionally, continuous GPS 18 km south of the central transect shows 4-5 mm/yr uplift between 2001 and 2004. Collectively, these data suggest a significant and smaller body inflating between 5-10 km depth and corresponding to 0.5-5× 106 m3 between 2002 and 2003. Though horizontal velocities are all less than their individual errors ( ˜5 mm) they generally radiate outward from the center of the SMB. These results indicate that the SMB may have considerable variation in the spatio-temporal pattern of deformation. This suggests that, though over several years to decades the SMB inflates at an average of 2-4 mm/yr, more frequent and widespread geodetic measurements are necessary to fully assess its complex sources. Additionally, because the southern portion of the SMB extends into the trilateration network of Savage et al. [1988], which found slow-to-no extension (<3 mm/yr) across the RGR, it may be that those results were contaminated by previously unknown transient

  4. Thermally-assisted Magma Emplacement Explains Restless Calderas

    Science.gov (United States)

    Amoruso, A.; Crescentini, L.; D'Antonio, M.; Acocella, V.

    2017-12-01

    Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei, Italy, which is the best-known, yet most dangerous calderas, lying to the west of Naples and restless since the 1950s at least.Our elaboration of the geodetic data indicates that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust.Our thermal models show that the repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth 3 ka before the last eruption and, in turn, contributed to maintain the thermal anomaly itself. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks.Available information at other calderas highlights similarities to Campi Flegrei, in the pattern and cause of unrest. All monitored restless calderas have either geodetically (Yellowstone, Aira Iwo-Jima, Askja, Fernandina and, partly, Long Valley) or geophysically (Rabaul, Okmok) detected sill-like intrusions inducing repeated unrest. Some calderas (Yellowstone, Long Valley) also show stable deformation pattern, where inflation insists on and mimics the resurgence uplift. The common existence of sill-like sources, also responsible for stable deformation patterns, in restless calderas suggests close similarities to Campi Flegrei. This suggests a wider applicability of our model of thermally-assisted sill emplacement, to be tested by future studies to better understand not only the dynamics of restless

  5. MAGMA: generalized gene-set analysis of GWAS data.

    Science.gov (United States)

    de Leeuw, Christiaan A; Mooij, Joris M; Heskes, Tom; Posthuma, Danielle

    2015-04-01

    By aggregating data for complex traits in a biologically meaningful way, gene and gene-set analysis constitute a valuable addition to single-marker analysis. However, although various methods for gene and gene-set analysis currently exist, they generally suffer from a number of issues. Statistical power for most methods is strongly affected by linkage disequilibrium between markers, multi-marker associations are often hard to detect, and the reliance on permutation to compute p-values tends to make the analysis computationally very expensive. To address these issues we have developed MAGMA, a novel tool for gene and gene-set analysis. The gene analysis is based on a multiple regression model, to provide better statistical performance. The gene-set analysis is built as a separate layer around the gene analysis for additional flexibility. This gene-set analysis also uses a regression structure to allow generalization to analysis of continuous properties of genes and simultaneous analysis of multiple gene sets and other gene properties. Simulations and an analysis of Crohn's Disease data are used to evaluate the performance of MAGMA and to compare it to a number of other gene and gene-set analysis tools. The results show that MAGMA has significantly more power than other tools for both the gene and the gene-set analysis, identifying more genes and gene sets associated with Crohn's Disease while maintaining a correct type 1 error rate. Moreover, the MAGMA analysis of the Crohn's Disease data was found to be considerably faster as well.

  6. Molten salt reactors. Synthesis of studies realized between 1973 and 1983. General synthesis

    International Nuclear Information System (INIS)

    Hery, M.; Lecocq, A.

    1983-03-01

    After a brief recall of the MSBR project, French studies on molten salt reactors are summed up. Theoretical and experimental studies for a graphite moderated 1000 MWe reactor using molten Li, Be, Th and U fluorides cooled by salt-lead direct contact are given. These studies concern the core, molten salt chemistry, graphite, metals (molybdenum, alloy TZM), corrosion, reactor components [fr

  7. Thermochemical investigation of molten fluoride salts for Generation IV nuclear applications - an equilibrium exercise

    NARCIS (Netherlands)

    van der Meer, J.P.M.

    2006-01-01

    The concept of the Molten Salt Reactor, one of the so-called Generation IV future reactors, is that the fuel, a fissile material, which is dissolved in a molten fluoride salt, circulates through a closed circuit. The heat of fission is transferred to a second molten salt coolant loop, the heat of

  8. The chlorine isotope fingerprint of the lunar magma ocean.

    Science.gov (United States)

    Boyce, Jeremy W; Treiman, Allan H; Guan, Yunbin; Ma, Chi; Eiler, John M; Gross, Juliane; Greenwood, James P; Stolper, Edward M

    2015-09-01

    The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free ("dry") Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because (37)Cl/(35)Cl ratios are not related to Cl abundance, H abundance, or D/H ratios in a manner consistent with the lava-outgassing hypothesis. Instead, (37)Cl/(35)Cl correlates positively with Cl abundance in apatite, as well as with whole-rock Th abundances and La/Lu ratios, suggesting that the high (37)Cl/(35)Cl in lunar basalts is inherited from urKREEP, the last dregs of the lunar magma ocean. These new data suggest that the high chlorine isotope ratios of lunar basalts result not from the degassing of their lavas but from degassing of the lunar magma ocean early in the Moon's history. Chlorine isotope variability is therefore an indicator of planetary magma ocean degassing, an important stage in the formation of terrestrial planets.

  9. Isotopic abundances relevant to the identification of magma sources

    International Nuclear Information System (INIS)

    O'Nions, R.K.

    1984-01-01

    The behaviour of natural radiogenic isotope tracers in the Earth that have lithophile and atmophile geochemical affinity is reviewed. The isotope tracer signature of oceanic and continental crust may in favourable circumstances by sufficiently distinct from that of the mantle to render a contribution from these sources resolvable within the isotopic composition of the magma. Components derived from the sedimentary and altered basaltic portion of oceanic crust are recognized in some island arc magmas from their Sr, Nd and Pb isotopic signatures. The rare-gas isotope tracers (He, Ar, Xe in particular) are not readily recycled into the mantle and thus provide the basis of an approach that is complementary to that based on the lithophile tracers. In particular, a small mantle-derived helium component may be readily recognized in the presence of a predominant radiogenic component generated in the continents. The importance of assessing the mass balance of these interactions rather than merely a qualitative recognition is emphasized. The question of the relative, contribution of continental-oceanic crust and mantle to magma sources is an essential part of the problem of generation and evolution of continental crust. An approach to this problem through consideration of the isotopic composition of sediments is briefly discussed. (author)

  10. Parental magmas of Mare Fecunditatis - Evidence from pristine glasses

    International Nuclear Information System (INIS)

    Jin, Y.; Taylor, L.A.

    1990-01-01

    Results are presented on the petrography and electron microprobe analyses of 14 discrete glass beads from the Luna 16 core sample (21036,15) from Mare Fecunditatis regolith, that were previously characterized as representing pristine glasses. Compared to Apollo pristine glasses analyzed by Delano (1986), the Luna 16 pristine glasses have higher CaO and Al2O3 contents but lower MgO and Ni. On the basis of their contents of MgO, FeO, Al2O3, and CaO, these pristine glasses could be divided into two groups, A and B. It is suggested that at least two parental magmas are needed to explain the chemical variations among these glasses. The Group B glasses appear to represent primitive parental magma that evolved by olivine fractionation to the compositions of the Luna 16 aluminous mare basalts, whereas the Group A volcanic glasses may represent an unusual new basalt magma type that contains a high plagioclase component. 14 refs

  11. Automatic Compound Annotation from Mass Spectrometry Data Using MAGMa.

    Science.gov (United States)

    Ridder, Lars; van der Hooft, Justin J J; Verhoeven, Stefan

    2014-01-01

    The MAGMa software for automatic annotation of mass spectrometry based fragmentation data was applied to 16 MS/MS datasets of the CASMI 2013 contest. Eight solutions were submitted in category 1 (molecular formula assignments) and twelve in category 2 (molecular structure assignment). The MS/MS peaks of each challenge were matched with in silico generated substructures of candidate molecules from PubChem, resulting in penalty scores that were used for candidate ranking. In 6 of the 12 submitted solutions in category 2, the correct chemical structure obtained the best score, whereas 3 molecules were ranked outside the top 5. All top ranked molecular formulas submitted in category 1 were correct. In addition, we present MAGMa results generated retrospectively for the remaining challenges. Successful application of the MAGMa algorithm required inclusion of the relevant candidate molecules, application of the appropriate mass tolerance and a sufficient degree of in silico fragmentation of the candidate molecules. Furthermore, the effect of the exhaustiveness of the candidate lists and limitations of substructure based scoring are discussed.

  12. Concentration variance decay during magma mixing: a volcanic chronometer.

    Science.gov (United States)

    Perugini, Diego; De Campos, Cristina P; Petrelli, Maurizio; Dingwell, Donald B

    2015-09-21

    The mixing of magmas is a common phenomenon in explosive eruptions. Concentration variance is a useful metric of this process and its decay (CVD) with time is an inevitable consequence during the progress of magma mixing. In order to calibrate this petrological/volcanological clock we have performed a time-series of high temperature experiments of magma mixing. The results of these experiments demonstrate that compositional variance decays exponentially with time. With this calibration the CVD rate (CVD-R) becomes a new geochronometer for the time lapse from initiation of mixing to eruption. The resultant novel technique is fully independent of the typically unknown advective history of mixing - a notorious uncertainty which plagues the application of many diffusional analyses of magmatic history. Using the calibrated CVD-R technique we have obtained mingling-to-eruption times for three explosive volcanic eruptions from Campi Flegrei (Italy) in the range of tens of minutes. These in turn imply ascent velocities of 5-8 meters per second. We anticipate the routine application of the CVD-R geochronometer to the eruptive products of active volcanoes in future in order to constrain typical "mixing to eruption" time lapses such that monitoring activities can be targeted at relevant timescales and signals during volcanic unrest.

  13. Making mushy magma chambers in the lower continental crust: Cold storage and compositional bimodality

    Science.gov (United States)

    Jackson, Matthew; Blundy, Jon; Sparks, Steve

    2017-04-01

    Increasing geological and geophysical evidence suggests that crustal magma reservoirs are normally low melt fraction 'mushes' rather than high melt fraction 'magma chambers'. Yet high melt fractions must form within these mush reservoirs to explain the observed flow and eruption of low crystallinity magmas. In many models, crystallinity is linked directly to temperature, with higher temperature corresponding to lower crystallinity (higher melt fraction). However, increasing temperature yields less evolved (silicic) melt composition for a given starting material. If mobile, low crystallinity magmas require high temperature, it is difficult to explain how they can have evolved composition. Here we use numerical modelling to show that reactive melt flow in a porous and permeable mush reservoir formed by the intrusion of numerous basaltic sills into the lower continental crust produces magma in high melt fraction (> 0.5) layers akin to conventional magma chambers. These magma-chamber-like layers contain evolved (silicic) melt compositions and form at low (close to solidus) temperatures near the top of the mush reservoir. Evolved magma is therefore kept in 'cold storage' at low temperature, but also at low crystallinity so the magma is mobile and can leave the mush reservoir. Buoyancy-driven reactive flow and accumulation of melt in the mush reservoir controls the temperature and composition of magma that can leave the reservoir. The modelling also shows that processes in lower crustal mush reservoirs produce mobile magmas that contain melt of either silicic or mafic composition. Intermediate melt compositions are present but are not within mobile magmas. Silicic melt compositions are found at high melt fraction within the magma-chamber like layers near the top of the mush reservoir. Mafic melt compositions are found at high melt fraction within the cooling sills. Melt elsewhere in the reservoir has intermediate composition, but remains trapped in the reservoir because

  14. Oxygen isotope study of the Long Valley magma system, California: isotope thermometry and convection in large silicic magma bodies

    Science.gov (United States)

    Bindeman, Ilya; Valley, John

    2002-07-01

    Products of voluminous pyroclastic eruptions with eruptive draw-down of several kilometers provide a snap-shot view of batholith-scale magma chambers, and quench pre-eruptive isotopic fractionations (i.e., temperatures) between minerals. We report analyses of oxygen isotope ratio in individual quartz phenocrysts and concentrates of magnetite, pyroxene, and zircon from individual pumice clasts of ignimbrite and fall units of caldera-forming 0.76 Ma Bishop Tuff (BT), pre-caldera Glass Mountain (2.1-0.78 Ma), and post-caldera rhyolites (0.65-0.04 Ma) to characterize the long-lived, batholith-scale magma chamber beneath Long Valley Caldera in California. Values of δ18O show a subtle 1‰ decrease from the oldest Glass Mountain lavas to the youngest post-caldera rhyolites. Older Glass Mountain lavas exhibit larger ( 1‰) variability of δ18O(quartz). The youngest domes of Glass Mountain are similar to BT in δ18O(quartz) values and reflect convective homogenization during formation of BT magma chamber surrounded by extremely heterogeneous country rocks (ranging from 2 to +29‰). Oxygen isotope thermometry of BT confirms a temperature gradient between "Late" (815 °C) and "Early" (715 °C) BT. The δ18O(quartz) values of "Early" and "Late" BT are +8.33 and 8.21‰, consistent with a constant δ18O(melt)=7.8+/-0.1‰ and 100 °C temperature difference. Zircon-melt saturation equilibria gives a similar temperature range. Values of δ18O(quartz) for different stratigraphic units of BT, and in pumice clasts ranging in pre-eruptive depths from 6 to 11 km (based on melt inclusions), and document vertical and lateral homogeneity of δ18O(melt). Worldwide, five other large-volume rhyolites, Lava Creek, Lower Bandelier, Fish Canyon, Cerro Galan, and Toba, exhibit equal δ18O(melt) values of earlier and later erupted portions in each of the these climactic caldera-forming eruptions. We interpret the large-scale δ18O homogeneity of BT and other large magma chambers as evidence

  15. Buffered and unbuffered dike emplacement on Earth and Venus - Implications for magma reservoir size, depth, and rate of magma replenishment

    Science.gov (United States)

    Parfitt, E. A.; Head, J. W., III

    1993-01-01

    Models of the emplacement of lateral dikes from magma chambers under constant (buffered) driving pressure conditions and declining (unbuffered) driving pressure conditions indicate that the two pressure scenarios lead to distinctly different styles of dike emplacement. In the unbuffered case, the lengths and widths of laterally emplaced dikes will be severely limited and the dike lengths will be highly dependent on chamber size; this dependence suggests that average dike length can be used to infer the dimensions of the source magma reservoir. On Earth, the characteristics of many mafic-dike swarms suggest that they were emplaced in buffered conditions (e.g., the Mackenzie dike swarm in Canada and some dikes within the Scottish Tertiary). On Venus, the distinctive radial fractures and graben surrounding circular to oval features and edifices on many size scales and extending for hundreds to over a thousand km are candidates for dike emplacement in buffered conditions.

  16. The roles of fractional crystallization, magma mixing, crystal mush remobilization and volatile-melt interactions in the genesis of a young basalt-peralkaline rhyolite suite, the greater Olkaria volcanic complex, Kenya Rift valley

    Science.gov (United States)

    Macdonald, R.; Belkin, H.E.; Fitton, J.G.; Rogers, N.W.; Nejbert, K.; Tindle, A.G.; Marshall, A.S.

    2008-01-01

    The Greater Olkaria Volcanic Complex is a young (???20 ka) multi-centred lava and dome field dominated by the eruption of peralkaline rhyolites. Basaltic and trachytic magmas have been erupted peripherally to the complex and also form, with mugearites and benmoreites, an extensive suite of magmatic inclusions in the rhyolites. The eruptive rocks commonly represent mixed magmas and the magmatic inclusions are themselves two-, three- or four-component mixes. All rock types may carry xenocrysts of alkali feldspar, and less commonly plagioclase, derived from magma mixing and by remobilization of crystal mushes and/or plutonic rocks. Xenoliths in the range gabbro-syenite are common in the lavas and magmatic inclusions, the more salic varieties sometimes containing silicic glass representing partial melts and ranging in composition from anorthite ?? corundum- to acmite-normative. The peralkaline varieties are broadly similar, in major element terms, to the eruptive peralkaline rhyolites. The basalt-trachyte suite formed by a combination of fractional crystallization, magma mixing and resorption of earlier-formed crystals. Matrix glass in metaluminous trachytes has a peralkaline rhyolitic composition, indicating that the eruptive rhyolites may have formed by fractional crystallization of trachyte. Anomalous trace element enrichments (e.g. ??? 2000 ppm Y in a benmoreite) and negative Ce anomalies may have resulted from various Na- and K-enriched fluids evolving from melts of intermediate composition and either being lost from the system or enriched in other parts of the reservoirs. A small group of nepheline-normative, usually peralkaline, magmatic inclusions was formed by fluid transfer between peralkaline rhyolitic and benmoreitic magmas. The plumbing system of the complex consists of several independent reservoirs and conduits, repeatedly recharged by batches of mafic magma, with ubiquitous magma mixing. ?? The Author 2008. Published by Oxford University Press. All

  17. Geochemical evidences of magma dynamics at Campi Flegrei (Italy)

    Science.gov (United States)

    Caliro, S.; Chiodini, G.; Paonita, A.

    2014-05-01

    Campi Flegrei caldera, within the Neapolitan area of Italy, is potentially one of the most dangerous volcanoes in the world, and during the last decade it has shown clear signs of reactivation, marked by the onset of uplift and changes in the geochemistry of gas emissions. We describe a 30-year-long data set of the CO2-He-Ar-N2 compositions of fumarolic emissions from La Solfatara crater, which is located in the center of the caldera. The data display continuous decreases in both the N2/He and N2/CO2 ratios since 1985, paralleled by an increase in He/CO2. These variations cannot be explained by either processes of boiling/condensation in the local hydrothermal system or with changes in the mixing proportions between a magmatic vapor and hydrothermal fluids. We applied the magma degassing model of Nuccio and Paonita (2001, Earth Planet. Sci. Lett. 193, 467-481) using the most recent inert-gas solubilities in order to interpret these peculiar features in accordance with petrologic constraints derived from the ranges of the melt compositions and reservoir pressures at Campi Flegrei. The model simulations for mafic melts (trachybasalt and shoshonite) show a remarkably good agreement with the measured data. Both decompressive degassing of an ascending magma and mixing between magmatic fluids exsolved at various levels along the ascent path can explain the long-term geochemical changes. Recalling that (i) a sill-like reservoir of gases at a depth of 3-4 km seems to be the main source of ground inflation and (ii) there is petrologic and geophysical evidence for a reservoir of magma at about 8 km below Campi Flegrei, we suggest that the most-intense episodes of inflation occur when the gas supply to the sill-like reservoir comes from the 8 km-deep magma, although fluids exsolved by magma bodies at shallower depths also contribute to the gas budget. Our work highlights that, in caldera systems where the presence of hydrothermal aquifers commonly masks the magmatic signature

  18. Computer Simulation To Assess The Feasibility Of Coring Magma

    Science.gov (United States)

    Su, J.; Eichelberger, J. C.

    2017-12-01

    Lava lakes on Kilauea Volcano, Hawaii have been successfully cored many times, often with nearly complete recovery and at temperatures exceeding 1100oC. Water exiting nozzles on the diamond core bit face quenches melt to glass just ahead of the advancing bit. The bit readily cuts a clean annulus and the core, fully quenched lava, passes smoothly into the core barrel. The core remains intact after recovery, even when there are comparable amounts of glass and crystals with different coefficients of thermal expansion. The unique resulting data reveal the rate and sequence of crystal growth in cooling basaltic lava and the continuous liquid line of descent as a function of temperature from basalt to rhyolite. Now that magma bodies, rather than lava pooled at the surface, have been penetrated by geothermal drilling, the question arises as to whether similar coring could be conducted at depth, providing fundamentally new insights into behavior of magma. This situation is considerably more complex because the coring would be conducted at depths exceeding 2 km and drilling fluid pressures of 20 MPa or more. Criteria that must be satisfied include: 1) melt is quenched ahead of the bit and the core itself must be quenched before it enters the barrel; 2) circulating drilling fluid must keep the temperature of the coring assembling cooled to within operational limits; 3) the drilling fluid column must nowhere exceed the local boiling point. A fluid flow simulation was conducted to estimate the process parameters necessary to maintain workable temperatures during the coring operation. SolidWorks Flow Simulation was used to estimate the effect of process parameters on the temperature distribution of the magma immediately surrounding the borehole and of drilling fluid within the bottom-hole assembly (BHA). A solid model of the BHA was created in SolidWorks to capture the flow behavior around the BHA components. Process parameters used in the model include the fluid properties and

  19. Magma Mixing: Magmatic Enclaves in Morne Micotrin, Dominica

    Science.gov (United States)

    Hickernell, S.; Frey, H. M.; Manon, M. R. F.; Waters, L. E.

    2017-12-01

    Magmatic enclaves in volcanic rocks provide direct evidence of magma mingling/mixing within a magma reservoir and may reinvigorate the system and trigger eruption, as documented at the Soufriere Hills in Montserrat. Lava domes on the neighboring island of Dominica also contain multiple enclave populations and may be evidence for similar magma chamber processes. The central dome of Micotrin is at the head of the Roseau Valley, which was filled with 3 km3 of pyroclastic deposits from eruptions spanning 65 - 25 ka. There appear to be two distinct types of enclaves in the crystal-rich Micotrin andesites (60 wt% SiO2), fine-grained and coarse-grained. Fine-grained mafic enclaves (52 wt% SiO2) vary in size from 1 to 15 cm in diameter, whereas the coarse-grained enclaves are generally larger and range from 3-20 cm. Fine-grained enclaves are saturated in plag (35%) + opx (35%) + cpx (20%) + oxides (10%). Average pyroxenes are 0.01 to 0.02 cm in size, whereas plagioclase averages 0.05 cm and up to 0.1 cm. The texture of the fine-grained enclaves is cumulate-like, devoid of microlites and matrix glass. Coarse-grained enclaves lack cpx and have different modal abundances and textures: plag (75%) + opx (10%) + oxides (5%) + plag microlites (10%). Plagioclase are 0.1 cm in size and orthopyroxenes average 0.05 cm. The coarse-grained enclaves are highly vesicular, a notable difference from the host as well as the fine-grained enclaves. The boundaries of both the fine- and coarse-grained enclaves are quite sharp and distinct and there do not appear to be enclave minerals disaggregated in the host rock. Temperatures were determined by two oxides. The fine-grained enclaves had two populations of magnetite, yielding 847 + 21° and 920 + 17°C. The coarse-grained enclave was 890 + 42 °C, but the oxides were extensively exsolved. Plagioclase composition in both coarse and fine-grained samples was comparable, ranging from An50 to An80. Despite compositional similarity the textures of

  20. Corrosion Behavior of Superalloys in Hot Lithium Molten Salt

    International Nuclear Information System (INIS)

    Cho, Soo-Haeng; Hur, Jin-Mok; Seo, Chung-Seok; Park, Seoung-Won

    2006-01-01

    The Li-reduction process involves the chemical reduction of spent fuel oxides by liquid lithium metal in a molten LiCl salt bath at 650 .deg. C followed by a separate electrochemical reduction of lithium oxide (Li 2 O), which builds up in the salt bath. This process requires a high purity inert gas atmosphere inside remote hot cell nuclear facility to prevent unwanted Li oxidation and fires during the handling of chemically active Li metal. In light of the limitations of the Li-reduction process, a direct electrolytic reduction technology is being developed by KAERI to enhance process safety and economic viability. The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. Even so, the electrochemical process vessel must be resilient at ∼ 650 .deg. C in the presence of oxygen to enable high processing rates and an extended service life. But, the mechanism and the rate of the corrosion of metals in LiCl-Li 2 O molten salt under oxidation condition are not clear. In the present work, the corrosion behavior and corrosion mechanism of superalloys have been studied in the molten salt of LiCl-Li 2 O under oxidation condition

  1. Study of an F center in molten KCl

    International Nuclear Information System (INIS)

    Parrinello, M.; Rahman, A.

    1983-05-01

    It is shown that a discretized version of Feynman's path integral provides a convenient tool for the numerical investigation of the properties of an electron solvated in molten KCl. The binding energy and the pair correlation functions are calculated. The local structure around the solute electron appears to be different from that of an F center in the solid

  2. Molten metal feed system controlled with a traveling magnetic field

    Science.gov (United States)

    Praeg, Walter F.

    1991-01-01

    A continuous metal casting system in which the feed of molten metal is controlled by means of a linear induction motor capable of producing a magnetic traveling wave in a duct that connects a reservoir of molten metal to a caster. The linear induction motor produces a traveling magnetic wave in the duct in opposition to the pressure exerted by the head of molten metal in the reservoir so that p.sub.c =p.sub.g -p.sub.m where p.sub.c is the desired pressure in the caster, p.sub.g is the gravitational pressure in the duct exerted by the force of the head of molten metal in the reservoir, and p.sub.m is the electromagnetic pressure exerted by the force of the magnetic field traveling wave produced by the linear induction motor. The invention also includes feedback loops to the linear induction motor to control the casting pressure in response to measured characteristics of the metal being cast.

  3. Experimental investigation of a molten salt thermocline storage tank

    Science.gov (United States)

    Yang, Xiaoping; Yang, Xiaoxi; Qin, Frank G. F.; Jiang, Runhua

    2016-07-01

    Thermal energy storage is considered as an important subsystem for solar thermal power stations. Investigations into thermocline storage tanks have mainly focused on numerical simulations because conducting high-temperature experiments is difficult. In this paper, an experimental study of the heat transfer characteristics of a molten salt thermocline storage tank was conducted by using high-temperature molten salt as the heat transfer fluid and ceramic particle as the filler material. This experimental study can verify the effectiveness of numerical simulation results and provide reference for engineering design. Temperature distribution and thermal storage capacity during the charging process were obtained. A temperature gradient was observed during the charging process. The temperature change tendency showed that thermocline thickness increased continuously with charging time. The slope of the thermal storage capacity decreased gradually with the increase in time. The low-cost filler material can replace the expensive molten salt to achieve thermal storage purposes and help to maintain the ideal gravity flow or piston flow of molten salt fluid.

  4. Treatment of plutonium process residues by molten salt oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Stimmel, J.; Wishau, R.; Ramsey, K.B.; Montoya, A.; Brock, J. [Los Alamos National Lab., NM (United States); Heslop, M. [Naval Surface Warfare Center (United States). Indian Head Div.; Wernly, K. [Molten Salt Oxidation Corp. (United States)

    1999-04-01

    Molten Salt Oxidation (MSO) is a thermal process that can remove more than 99.999% of the organic matrix from combustible {sup 238}Pu material. Plutonium processing residues are injected into a molten salt bed with an excess of air. The salt (sodium carbonate) functions as a catalyst for the conversion of the organic material to carbon dioxide and water. Reactive species such as fluorine, chlorine, bromine, iodine, sulfur, phosphorous and arsenic in the organic waste react with the molten salt to form the corresponding neutralized salts, NaF, NaCl, NaBr, NaI, Na{sub 2}SO{sub 4}, Na{sub 3}PO{sub 4} and NaAsO{sub 2} or Na{sub 3}AsO4. Plutonium and other metals react with the molten salt and air to form metal salts or oxides. Saturated salt will be recycled and aqueous chemical separation will be used to recover the {sup 238}Pu. The Los Alamos National Laboratory system, which is currently in the conceptual design stage, will be scaled down from current systems for use inside a glovebox.

  5. Thermodynamic characterization of salt components for Molten Salt Reactor fuel

    NARCIS (Netherlands)

    Capelli, E.

    2016-01-01

    The Molten Salt Reactor (MSR) is a promising future nuclear fission reactor technology with excellent performance in terms of safety and reliability, sustainability, proliferation resistance and economics. For the design and safety assessment of this concept, it is extremely important to have a

  6. Probability safety assessment of LOOP accident to molten salt reactor

    International Nuclear Information System (INIS)

    Mei Mudan; Shao Shiwei; Yu Zhizhen; Chen Kun; Zuo Jiaxu

    2013-01-01

    Background: Loss of offsite power (LOOP) is a possible accident to any type of reactor, and this accident can reflect the main idea of reactor safety design. Therefore, it is very important to conduct a study on probabilistic safety assessment (PSA) of the molten salt reactor that is under LOOP circumstance. Purpose: The aim is to calculate the release frequency of molten salt radioactive material to the core caused by LOOP, and find out the biggest contributor to causing the radioactive release frequency. Methods: We carried out the PSA analysis of the LOOP using the PSA process risk spectrum, and assumed that the primary circuit had no valve and equipment reliability data based on the existing mature power plant equipment reliability data. Results: Through the PSA analysis, we got the accident sequences of the release of radioactive material to the core caused by LOOP and its frequency. The results show that the release frequency of molten salt radioactive material to the core caused by LOOP is about 2×10 -11 /(reactor ·year), which is far below that of the AP1000 LOOP. In addition, through the quantitative analysis, we obtained the point estimation and interval estimation of uncertainty analysis, and found that the biggest contributor to cause the release frequency of radioactive material to the core is the reactor cavity cooling function failure. Conclusion: This study provides effective help for the design and improvement of the following molten salt reactor system. (authors)

  7. Nuclear energy synergetics and molten-salt technology

    International Nuclear Information System (INIS)

    Furukawa, Kazuo

    1988-01-01

    There are various problems with nuclear energy techniques in terms of resources, safety, environmental effects, nuclear proliferation, reactor size reduction and overall economics. To overcome these problems, future studies should be focused on utilization of thorium resources, separation of multiplication process and power generation process, and application of liquid nuclear fuel. These studies will lead to the development of molten thorium salt nuclear synergetics. The most likely candidate for working medium is Lif-BeF 2 material (flibe). 233 U production facilities are required for the completion of the Th cycle. For this, three ideas have been proposed: accelerator M.S. breeder, impact fusion MSB and inertial conf. fusion hybrid MSB. The first step toward the development of molten Th salt nuclear energy synergetics will be the construction of a pilot plant of an extreme small size. As candidate reactor, the author has selected mini FUJI-II (7.0 MWe), an extremely small molten salt power reactor. Mini FUJI-II facilities are expected to be developed in 7 - 8 years. For the next step (demonstration step), the designing of a small power reactor (FUJI 160 MWe) has already been carried out. A small molten salt reactor will have good safety characteristics in terms of chemistry, material, structure, nuclear safety and design basis accidents. Such reactors will also have favorable economic aspects. (Nogami, K.)

  8. Nonmetal-metal transition in metal–molten-salt solutions

    NARCIS (Netherlands)

    Silvestrelli, P.-L.; Alavi, A.; Parrinello, M.; Frenkel, D.

    1996-01-01

    The method of ab initio molecular dynamics, based on finite-temperature density-functional theory, is used to study the nonmetal-metal transition in two different metal–molten-salt solutions, Kx(KCl)1-x and Nax(NaBr)1-x. As the excess metal concentration is increased the electronic density becomes

  9. Study of an F center in molten KCl

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1983-05-01

    It is shown that a discretized version of Feynman's path integral provides a convenient tool for the numerical investigation of the properties of an electron solvated in molten KCl. The binding energy and the pair correlation functions are calculated. The local structure around the solute electron appears to be different from that of an F center in the solid.

  10. Candidate molten salt investigation for an accelerator driven subcritical core

    Energy Technology Data Exchange (ETDEWEB)

    Sooby, E., E-mail: soobyes@tamu.edu [Texas A and M University, Accelerator Research Laboratory, 3380 University Dr. East, College Station, TX 77845 (United States); Baty, A. [Texas A and M University, Accelerator Research Laboratory, 3380 University Dr. East, College Station, TX 77845 (United States); Beneš, O. [European Commission, DG Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); McIntyre, P.; Pogue, N. [Texas A and M University, Accelerator Research Laboratory, 3380 University Dr. East, College Station, TX 77845 (United States); Salanne, M. [Université Pierre et Marie Curie, CNRS, Laboratoire PECSA, F-75005 Paris (France); Sattarov, A. [Texas A and M University, Accelerator Research Laboratory, 3380 University Dr. East, College Station, TX 77845 (United States)

    2013-09-15

    Highlights: • Developing accelerator driven subcritical fission to destroy transuranics in SNF. • The core is a vessel containing a molten mixture of NaCl and transuranic chlorides. • Molecular dynamics used to calculate the thermophysical properties of the salt. • Density and molecular structure for actinide salts reported here. • The neutronics of ADS fission in molten salt are presented. -- Abstract: We report a design for accelerator-driven subcritical fission in a molten salt core (ADSMS) that utilizes a fuel salt composed of NaCl and transuranic (TRU) chlorides. The ADSMS core is designed for fast neutronics (28% of neutrons >1 MeV) to optimize TRU destruction. The choice of a NaCl-based salt offers benefits for corrosion, operating temperature, and actinide solubility as compared with LiF-based fuel salts. A molecular dynamics (MD) code has been used to estimate properties of the molten salt system which are important for ADSMS design but have never been measured experimentally. Results from the MD studies are reported. Experimental measurements of fuel salt properties and studies of corrosion and radiation damage on candidate metals for the core vessel are anticipated.

  11. Sorbitol dehydration into isosorbide in a molten salt hydrate medium

    NARCIS (Netherlands)

    Li, J.; Spina, A.; Moulijn, J.A.; Makkee, M.

    2013-01-01

    The sorbitol conversion in a molten salt hydrate medium (ZnCl2; 70 wt% in water) was studied. Dehydration is the main reaction, initially 1,4- and 3,6-anhydrosorbitol are the main products that are subsequently converted into isosorbide; two other anhydrohexitols, (1,5- and 2,5-), formed are in less

  12. Raman spectra of zirconium tetrachloride in molten and evaporational states

    International Nuclear Information System (INIS)

    Salyuev, A.B.; Kornyakova, I.D.

    1994-01-01

    For the first time raman spectra of ZrCl 4 are obtained in the temperature range of its existence in molten state as well as in vapors near the critical point. It is shown, that rupture of zigzag chains is taking place when ZrCl 4 is melting

  13. Candidate molten salt investigation for an accelerator driven subcritical core

    International Nuclear Information System (INIS)

    Sooby, E.; Baty, A.; Beneš, O.; McIntyre, P.; Pogue, N.; Salanne, M.; Sattarov, A.

    2013-01-01

    Highlights: • Developing accelerator driven subcritical fission to destroy transuranics in SNF. • The core is a vessel containing a molten mixture of NaCl and transuranic chlorides. • Molecular dynamics used to calculate the thermophysical properties of the salt. • Density and molecular structure for actinide salts reported here. • The neutronics of ADS fission in molten salt are presented. -- Abstract: We report a design for accelerator-driven subcritical fission in a molten salt core (ADSMS) that utilizes a fuel salt composed of NaCl and transuranic (TRU) chlorides. The ADSMS core is designed for fast neutronics (28% of neutrons >1 MeV) to optimize TRU destruction. The choice of a NaCl-based salt offers benefits for corrosion, operating temperature, and actinide solubility as compared with LiF-based fuel salts. A molecular dynamics (MD) code has been used to estimate properties of the molten salt system which are important for ADSMS design but have never been measured experimentally. Results from the MD studies are reported. Experimental measurements of fuel salt properties and studies of corrosion and radiation damage on candidate metals for the core vessel are anticipated

  14. Molten salt scrubbing of zirconium or hafnium tetrachloride

    International Nuclear Information System (INIS)

    Lee, E.D.; McLaughlin, D.F.

    1990-01-01

    This patent describes a continuous process for removing impurities of iron or aluminum chloride or both from vaporous zirconium or hafnium chloride or both. It comprises: introducing impure zirconium or hafnium chloride vapor or both into a middle portion of an absorbing column containing a molten salt phase, the molten salt phase absorbing the impurities of iron or aluminum chloride or both to produce chloride vapor stripped of zirconium or hafnium chloride; introducing sodium or potassium chloride or both into a top portion of the column; controlling the top portion of the column to between 300--375 degrees C.; heating a bottom portion of the column to 450--550 degrees C. To vaporize zirconium chloride or hafnium chloride or hafnium and zirconium chloride from the molten salt; withdrawing molten salt substantially free of zirconium and hafnium chloride from the bottom portion of the column; and withdrawing zirconium chloride or hafnium chloride or hafnium and zirconium chloride vapor substantially free of impurities of iron and aluminum chloride from the top of the column

  15. Nickel catalysts for internal reforming in molten carbonate fuel cells

    NARCIS (Netherlands)

    Berger, R.J.; Berger, R.J.; Doesburg, E.B.M.; Doesburg, E.B.M.; van Ommen, J.G.; Ross, J.R.H.; Ross, J.R.H.

    1996-01-01

    Natural gas may be used instead of hydrogen as fuel for the molten carbonate fuel cell (MCFC) by steam reforming the natural gas inside the MCFC, using a nickel catalyst (internal reforming). The severe conditions inside the MCFC, however, require that the catalyst has a very high stability. In

  16. Conduit for high temperature transfer of molten semiconductor crystalline material

    Science.gov (United States)

    Fiegl, George (Inventor); Torbet, Walter (Inventor)

    1983-01-01

    A conduit for high temperature transfer of molten semiconductor crystalline material consists of a composite structure incorporating a quartz transfer tube as the innermost member, with an outer thermally insulating layer designed to serve the dual purposes of minimizing heat losses from the quartz tube and maintaining mechanical strength and rigidity of the conduit at the elevated temperatures encountered. The composite structure ensures that the molten semiconductor material only comes in contact with a material (quartz) with which it is compatible, while the outer layer structure reinforces the quartz tube, which becomes somewhat soft at molten semiconductor temperatures. To further aid in preventing cooling of the molten semiconductor, a distributed, electric resistance heater is in contact with the surface of the quartz tube over most of its length. The quartz tube has short end portions which extend through the surface of the semiconductor melt and which are lef bare of the thermal insulation. The heater is designed to provide an increased heat input per unit area in the region adjacent these end portions.

  17. Visualization of steam bubbles with evaporation in molten alloy

    International Nuclear Information System (INIS)

    Nishi, Yoshihisa; Furuya, Masahiro; Kinoshita, Izumi; Takenaka, Nobuyuki; Matsubayashi, Masahito

    1997-01-01

    An innovative Steam Generator concept of Fast Breeder Reactors by using liquid-liquid direct contact heat transfer has been developed. In this concept, the SG shell is filled with a molten alloy heated by primary sodium. Water is fed into the high temperature molten alloy, and evaporates by direct contact heating. In order to obtain the fundamental information to discuss the heat transfer mechanisms of the direct contact between the water and the molten alloy, this phenomenon was visualized by neutron radiography. JRR-3M radiography in Japan Atomic Energy Research Institute was used. Followings are main results. (1) The bubbles with evaporation are risen with vigorous form changing, coalescence and break-up. Because of these vigorous evaporation, this system have the high heat transfer performance. (2) The rising velocities and volumes of bubbles are calculated from pixcel values of images. The velocities of the bubbles with evaporation are about 60 cm/s, which is larger than that of inert gas bubbles in molten alloy (20-40 cm/s). (3) The required heat transfer length of evaporation is calculated from pixcel values of images. The relation between heat transfer length and superheat temperature, obtained through the heat transfer test, is conformed by this calculation. (author)

  18. Fluid Mechanics Of Molten Metal Droplets In Additive Manufacturing

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav; Šonský, Jiří

    2016-01-01

    Roč. 4, č. 4 (2016), s. 403-412 ISSN 2046-0546 R&D Projects: GA ČR GA13-23046S Institutional support: RVO:61388998 Keywords : additive manufacturing * droplets * molten metal Subject RIV: BK - Fluid Dynamics http://www.witpress.com/elibrary/cmem-volumes/4/4/1545

  19. Research and development issues for molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Krumpelt, M.

    1996-04-01

    This paper describes issues pertaining to the development of molten carbonate fuel cells. In particular, the corrosion resistance and service life of nickel oxide cathodes is described. The resistivity of lithium oxide/iron oxides and improvement with doping is addressed.

  20. Release properties of UC sub x and molten U targets

    CERN Document Server

    Roussière, B; Sauvage, J; Bajeat, O; Barre, N; Clapier, F; Cottereau, E; Donzaud, C; Ducourtieux, M; Essabaa, S; Guillemaud-Müller, D; Lau, C; Lefort, H; Liang, C F; Le Blanc, F; Müller, A C; Obert, J; Pauwels, N; Potier, J C; Pougheon, F; Proust, J; Sorlin, O; Verney, D; Wojtasiewicz, A

    2002-01-01

    The release properties of UC sub x and molten U thick targets associated with a Nier-Bernas ion source have been studied. Two experimental methods are used to extract the release time. Results are presented and discussed for Kr, Cd, I and Xe.

  1. Thorium and Molten Salt Reactors: "Essential Questions for Classroom Discussions"

    Science.gov (United States)

    DiLisi, Gregory A.; Hirsch, Allison; Murray, Meredith; Rarick, Richard

    2018-01-01

    A little-known type of nuclear reactor called the "molten salt reactor" (MSR), in which nuclear fuel is dissolved in a liquid carrier salt, was proposed in the 1940s and developed at the Oak Ridge National Laboratory in the 1960s. Recently, the MSR has generated renewed interest as a remedy for the drawbacks associated with conventional…

  2. Treatment of plutonium process residues by molten salt oxidation

    International Nuclear Information System (INIS)

    Stimmel, J.; Wishau, R.; Ramsey, K.B.; Montoya, A.; Brock, J.; Heslop, M.

    1999-01-01

    Molten Salt Oxidation (MSO) is a thermal process that can remove more than 99.999% of the organic matrix from combustible 238 Pu material. Plutonium processing residues are injected into a molten salt bed with an excess of air. The salt (sodium carbonate) functions as a catalyst for the conversion of the organic material to carbon dioxide and water. Reactive species such as fluorine, chlorine, bromine, iodine, sulfur, phosphorous and arsenic in the organic waste react with the molten salt to form the corresponding neutralized salts, NaF, NaCl, NaBr, NaI, Na 2 SO 4 , Na 3 PO 4 and NaAsO 2 or Na 3 AsO4. Plutonium and other metals react with the molten salt and air to form metal salts or oxides. Saturated salt will be recycled and aqueous chemical separation will be used to recover the 238 Pu. The Los Alamos National Laboratory system, which is currently in the conceptual design stage, will be scaled down from current systems for use inside a glovebox

  3. Time-of-flight pulsed neutron diffraction of molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Y; Misawa, M; Suzuki, K [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1975-06-01

    In this work, the pulsed neutron diffraction of molten alkali metal nitrate and bismuth trihalide was measured by the time-of-flight method. An electron linear accelerator was used as the pulsed neutron source. All the measurements were carried out with the T-O-F neutron diffractometer installed on the 300 MeV electron lineac. Molten NaNO/sub 3/ and RbNO/sub 3/ were adopted as the samples for alkali metal nitrate. The measurement is in progress for KNO/sub 3/ and LiNO/sub 3/. As the first step of the study on bismuth-bismuth trihalide system, the temperature dependence of structure factors was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/ in the liquid state. The structure factors Sm(Q) for molten NaNO/sub 3/ at 340/sup 0/C and RbNO/sub 3/ at 350/sup 0/C were obtained, and the form factor F/sub 1/(Q) for single NO/sub 3//sup -/ radical with equilateral triangle structure was calculated. In case of molten NaNO/sub 3/, the first peak of Sm(Q) is simply smooth and a small hump can be observed in the neighbourhood of the first minimum Q position. The first peak of Sm(Q) for molten RbNO/sub 3/ is divided into two peaks, whereas a hump at the first minimum becomes big, and shifts to the low Q side of the second peak. The size of the NO/sub 3//sup -/ radical in molten NaNO/sub 3/ is a little smaller than that in molten RbNO/sub 3/. The values of the bond length in the NO/sub 3//sup -/ radical are summarized for crystal state and liquid state. The temperature dependence of the structure factor S(Q) was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/, and shown in a figure.

  4. Molar Volume Analysis of Molten Ni-Al-Co Alloy by Measuring the Density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang; FU Yuechao; YANG Lingchuan

    2004-01-01

    The density of molten Ni-Al-Co alloys was measured in the temperature range of 1714~1873K using a modified pycnometric method, and the molar volume of molten alloys was analyzed. The density of molten Ni-Al-Co alloys was found to decrease with increasing temperature and Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys increases with increasing Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys shows a negative deviation from the linear molar volume.

  5. Supplying Fe from molten coal ash to revive kelp community

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, K.; Yamamoto, M.; Sadakata, M. [University of Tokyo, Tokyo (Japan)

    2006-02-15

    The phenomenon of a kelp-dominated community changing to a crust-dominated community, which is called 'barren-ground', is progressing in the world, and causing serious social problems in coastal areas. Among several suggested causes of 'barren-ground', we focused on the lack of Fe in seawater. Kelp needs more than 200 nM of Fe to keep its community. However there are the areas where the concentration of Fe is less than 1 nM, and the lack of Fe leads to the 'barren-ground.' Coal ash is one of the appropriate materials to compensate the lack of Fe for the kelp growth, because the coal ash is a waste from the coal combustion process and contains more than 5 wt% of Fe. The rate of Fe elution from coal fly ash to water can be increased by 20 times after melting in Ar atmosphere, because 39 wt% of the Fe(III) of coal fly ash was reduced to Fe(II). Additionally molten ash from the IGCC (integrated coal gasification combined cycle) furnace in a reducing atmosphere and one from a melting furnace pilot plant in an oxidizing atmosphere were examined. Each molten ash was classified into two groups; cooled rapidly with water and cooled slowly without water. The flux of Fe elution from rapidly cooled IGCC molten ash was the highest; 9.4 x 10{sup -6} g m{sup -2} d{sup -1}. It was noted that the coal ash melted in a reducing atmosphere could elute Fe effectively, and the dissolution of the molten ash itself controlled the rate of Fe elution in the case of rapidly cooled molten ash.

  6. Propagation mechanisms of molten fuel/moderator interactions

    International Nuclear Information System (INIS)

    Frost, D.L.; Ciccarelli, G.

    1991-06-01

    It is well known that a vapor explosion can result when molten is suddenly brought into contact with a cold volatile liquid such as water. However, the rapid melt fragmentation and heat transfer processes that occur during a propagating melt-water interaction are poorly understood. Experiments were carried out in the present work to investigate the fragmentation processes for single molten metal drops in water. To determine the time scale for the fragmentation of a drop, liquid metal drops (in thermal equilibrium with the water) as well as hot molten drops surrounded by a vapor film were subjected to underwater shocks with overpressures of up to about 20 MPa. In the hot molten drop tests, the induction time for the initiation of the explosion is typically less than 100 μs; at a corresponding time in the cold drop tests, very little or no direct hydrodynamic fragmentation of the drop has occurred. Therefore, in the hot drop case the fragmentation of the drop is dominated by thermal effects; i.e., the heat transfer from the melt to the water leads to violent boiling, pressurization, and drop fragmentation. The melt-water interaction consists of several cycles involving bubble growth and collapse. The strength of the interaction was not found to be a strong function of initial shock pressure (for molten tin drops with trigger pressures of up to 20 MPa), but depends on the thermal energy in the melt: high-temperature thermite drops generated a larger first bubble than lower temperature melt drops. A model for the fine fragmentation process for a hot drop is proposed that is based on thermal effects. The fragmentation processes governed by thermal effects observed in the present experiments are expected to play an important role in the escalation of a local interaction to a large-scale coherent vapor explosion, and are not accounted for in current transient models for propagating vapor explosions

  7. Molten salt oxidation as an alternative to incineration

    International Nuclear Information System (INIS)

    Gray, L.W.; Adamson, M.G.; Cooper, J.F.; Farmer, J.C.; Upadhye, R.S.

    1992-03-01

    Molten Salt Oxidation was originally developed by Rockwell International as part of their coal gasification, and nuclear-and hazardous-waste treatment programs. Single-stage oxidation units employing molten carbonate salt mixtures were found to process up to one ton/day of common solid and liquid wastes (such as paper, rags, plastics, and solvents), and (in larger units) up to one ton/hour of coal. After the oxidation of coal with excess oxygen, coal ash residuals (alumina-silicates) were found adhering to the vessel walls above the liquid level. The phenomenon was not observed with coal gasification-i.e., under oxygen-deficient conditions. Lawrence Livermore National Laboratory (LLNL) is developing a two-stage/two-vessel approach as a possible means of extending the utility of the process to wastes which contain high concentrations of alumina-silicates in the form of soils or clays, or high concentrations of nitrates including low-level and transuranic wastes. The first stage operates under oxygen-deficient (''pyrolysis'') conditions; the second stage completes oxidation of the evolved gases. The process allows complete oxidation of the organic materials without an open flame. In addition, all acidic gases that would be generated in incinerators are directly metathesized via the molten Na 2 CO 3 to form stable salts (NaCl, Na 2 SO 4 etc.). Molten salt oxidation therefore avoids the corrosion problems associated with free HCl in incineration. The process is being developed to use pure O 2 feeds in lieu of air, in order to reduce offgas volume and retain the option of closed system operation. In addition, ash is wetted and retained in the melt of the first vessel which must be replaced (continuously or batch-wise). The LLNL Molten Salt unit is described together with the initial operating data

  8. Magma viscosity estimation based on analysis of erupted products. Potential assessment for large-scale pyroclastic eruptions

    International Nuclear Information System (INIS)

    Takeuchi, Shingo

    2010-01-01

    After the formulation of guidelines for volcanic hazards in site evaluation for nuclear installations (e.g. JEAG4625-2009), it is required to establish appropriate methods to assess potential of large-scale pyroclastic eruptions at long-dormant volcanoes, which is one of the most hazardous volcanic phenomena on the safety of the installations. In considering the volcanic dormancy, magma eruptability is an important concept. The magma eruptability is dominantly controlled by magma viscosity, which can be estimated from petrological analysis of erupted materials. Therefore, viscosity estimation of magmas erupted in past eruptions should provide important information to assess future activities at hazardous volcanoes. In order to show the importance of magma viscosity in the concept of magma eruptability, this report overviews dike propagation processes from a magma chamber and nature of magma viscosity. Magma viscosity at pre-eruptive conditions of magma chambers were compiled based on previous petrological studies on past eruptions in Japan. There are only 16 examples of eruptions at 9 volcanoes satisfying data requirement for magma viscosity estimation. Estimated magma viscosities range from 10 2 to 10 7 Pa·s for basaltic to rhyolitic magmas. Most of examples fall below dike propagation limit of magma viscosity (ca. 10 6 Pa·s) estimated based on a dike propagation model. Highly viscous magmas (ca. 10 7 Pa·s) than the dike propagation limit are considered to lose eruptability which is the ability to form dikes and initiate eruptions. However, in some cases, small precursory eruptions of less viscous magmas commonly occurred just before climactic eruptions of the highly viscous magmas, suggesting that the precursory dike propagation by the less viscous magmas induced the following eruptions of highly viscous magmas (ca. 10 7 Pa·s). (author)

  9. Transfer characteristics of a lithium chloride–potassium chloride molten salt

    Directory of Open Access Journals (Sweden)

    Eve Mullen

    2017-12-01

    Full Text Available Pyroprocessing is an alternative method of reprocessing spent fuel, usually involving the dissolving spent fuel in a molten salt media. The National Nuclear Laboratory designed, built, and commissioned a molten salt dynamics rig to investigate the transfer characteristics of molten lithium chloride–potassium chloride eutectic salt. The efficacy and flow characteristics of a high-temperature centrifugal pump and argon gas lift were obtained for pumping the molten salt at temperatures up to 500°C. The rig design proved suitable on an industrial scale and transfer methods appropriate for use in future molten salt systems. Corrosion within the rig was managed, and melting techniques were optimized to reduce stresses on the rig. The results obtained improve the understanding of molten salt transport dynamics, materials, and engineering design issues and support the industrialization of molten salts pyroprocessing.

  10. CAMDYN: a new model to describe the axial motion of molten fuel inside the pin of a fast breeder reactor during accident conditions

    International Nuclear Information System (INIS)

    Peter, G.

    1991-01-01

    The new in-pin fuel motion model CAMDYN (Cavity Material Dynamics) describes the axial motion of both partially and fully molten fuel inside the pin of a fast breeder reactor during accident conditions. The motion of the two types of molten fuel and the imbedded fission gas bubbles is treated both before and after cladding failure. The basic modelling approach consists of the treatment of two one-dimensional flows which are coupled by interaction terms. Each of these flows is treated compressively and with axially variable flow cross sections. The mass and energy equations of both fields are solved explicitly using upwind differencing on a fixed Eulerian grid. The two momentum equations are solved simultaneously, using the convective momentum fluxes of the previous timestep. Both partially and fully molten fuel can move axially into a central hole extending to the plenum in the case of certain hollow pellet designs. The fuel temperature calculation includes the determination of a radial temperature profile. A simple conduction freezing model is included. After cladding failure, ejection into the coolant channel is modeled

  11. Radioactive equilibria and disequilibria of U-series nuclides in erupting magmas from Izu arc volcanoes

    International Nuclear Information System (INIS)

    Sato, Jun; Kurihara, Yuichi; Takahashi, Masaomi

    2009-01-01

    Radioactive disequilibria among U-series nuclides are observed in the magmas from volcanoes in the world. Basaltic products from Izu arc volcanoes, including Izu-Oshima and Fuji volcanoes, show 230 Th 238 U and 226 Ra> 230 Th disequilibria, indicating that the addition of U-and Ra-rich fluid from the subducting slab to the mantle wedge at the magma genesis. The disequilibria of 226 Ra> 230 Th in the erupting magmas suggest that the timescale from magma genesis to the eruption may be less than 8000 years. (author)

  12. Sr- and Nd- isotope variations along the Pleistocene San Pedro - Linzor volcanic chain, N. Chile: Tracking the influence of the upper crustal Altiplano-Puna Magma Body

    Science.gov (United States)

    Godoy, Benigno; Wörner, Gerhard; Le Roux, Petrus; de Silva, Shanaka; Parada, Miguel Ángel; Kojima, Shoji; González-Maurel, Osvaldo; Morata, Diego; Polanco, Edmundo; Martínez, Paula

    2017-07-01

    Subduction-related magmas that erupted in the Central Andes during the past 10 Ma are strongly affected by crustal assimilation as revealed by an increase in 87Sr/86Sr isotope ratios with time that in turn are correlated with increased crustal thickening during the Andean orogeny. However, contamination is not uniform and can be strongly influenced locally by crustal composition, structure and thermal condition. This appears to be the case along the NW-SE San Pedro - Linzor volcanic chain (SPLVC) in northern Chile, which straddles the boundary of a major zone of partial melt, the Altiplano_Puna Magma Body (APMB). Herein we report 40Ar/39Ar ages, compositional and isotope data on lavas from the SPLVC that track the influence of this zone of partial melting on erupted lavas with geochronological and geochemical data. Ages reported here indicate that SPLVC has evolved in the last 2 M.y., similar to other volcanoes of the Western Cordillera (e.g. Lascar, Uturuncu, Putana). 87Sr/86Sr ratios increase systematically along the chain from a minimum value of 0.7057 in San Pedro dacites to a maximum of 0.7093-0.7095 for the Toconce and Cerro de Leon dacites in the SE. These changes are interpreted to reflect the increasing interaction of SPLVC parental magmas with partial melt within the APMB eastwards across the chain. The 87Sr/86Sr ratio and an antithetic trend in 143Nd/144Nd is therefore a proxy for the contribution of melt from the APMB beneath this volcanic chain. Similar 87Sr/86Sr increases and 143Nd/144Nd decreases are observed in other transects crossing the boundary of the APMB. Such trends can be recognized from NW to SE between Aucanquilcha, Ollagüe, and Uturuncu volcanoes, and from Lascar volcano to the N-S-trending Putana-Sairecabur-Licancabur volcanic chain to the north. We interpret these isotopic trends as reflecting different degrees of interaction of mafic parental melts with the APMB. High 87Sr/86Sr, and low 143Nd/144Nd reveal zones where the APMB is

  13. Pourbaix diagrams of actinides in molten chlorides using an indicating electrode for oxide ion activity

    International Nuclear Information System (INIS)

    Lambertin, D.; Lacquement, J.

    2000-01-01

    Pyrochemical separation methods using high temperature molten salt media could emerge as promising and valuable routes compared with aqueous methods for separation and transmutation strategies for long-lived radionuclides. A good knowledge of the molten salt chemistry is essential for controlling these separations, and elementary data are required for molten halide salts, which can be readily provided by electrochemical methods. Applying the chemical principles of aqueous solutions to the molten salt media, Pourbaix diagrams - called in this case potential-oxo-acidity (pO 2- ) - can be plotted. They offer a rapid and comprehensive view of the thermodynamic properties of selected elements in a solvent of interest. Two methods are available for preparing these diagrams. The first is based on available thermodynamic data on pure element oxide (and oxychloride) compounds and on element chloride activity coefficients in melt (which can be electrochemically determined). In this method, we consider the oxide anion exchange reactions between the pure compounds, water and hydrogen chloride. The second method is a direct and experimental determination of the oxo-acidic properties of the studied element chlorides in melts. Use of an Yttria-Stabilised Zirconia Membrane (YSZM) electrode (oxide anion selective electrode) helps determine the nature of the stable oxide compounds in melts as well as their stabilities. The YSZM is used with a silver/silver chloride reference system, and was developed 25 years ago. Two examples of Potential-acidity diagrams. Employing the first method and the determination of the standard potential of plutonium in LiCl-KCl and NaCl-KCl eutectic mixtures, potential-oxo-acidity diagrams were plotted for these melts at various temperatures. It was found that the stability domain for plutonium chloride depends on the melt composition (influence of oxide anion solvation). We also used the Omega acidity function - based on reaction (1) - which is a

  14. Long-Term Volumetric Eruption Rates and Magma Budgets

    Energy Technology Data Exchange (ETDEWEB)

    Scott M. White Dept. Geological Sciences University of South Carolina Columbia, SC 29208; Joy A. Crisp Jet Propulsion Laboratory, California Institute of Technology Pasadena, CA 91109; Frank J. Spera Dept. Earth Science University of California, Santa Barbara Santa Barbara, CA 93106

    2005-01-01

    A global compilation of 170 time-averaged volumetric volcanic output rates (Qe) is evaluated in terms of composition and petrotectonic setting to advance the understanding of long-term rates of magma generation and eruption on Earth. Repose periods between successive eruptions at a given site and intrusive:extrusive ratios were compiled for selected volcanic centers where long-term (>104 years) data were available. More silicic compositions, rhyolites and andesites, have a more limited range of eruption rates than basalts. Even when high Qe values contributed by flood basalts (9 ± 2 Å~ 10-1 km3/yr) are removed, there is a trend in decreasing average Qe with lava composition from basaltic eruptions (2.6 ± 1.0 Å~ 10-2 km3/yr) to andesites (2.3 ± 0.8 Å~ 10-3 km3/yr) and rhyolites (4.0 ± 1.4 Å~ 10-3 km3/yr). This trend is also seen in the difference between oceanic and continental settings, as eruptions on oceanic crust tend to be predominately basaltic. All of the volcanoes occurring in oceanic settings fail to have statistically different mean Qe and have an overall average of 2.8 ± 0.4 Å~ 10-2 km3/yr, excluding flood basalts. Likewise, all of the volcanoes on continental crust also fail to have statistically different mean Qe and have an overall average of 4.4 ± 0.8 Å~ 10-3 km3/yr. Flood basalts also form a distinctive class with an average Qe nearly two orders of magnitude higher than any other class. However, we have found no systematic evidence linking increased intrusive:extrusive ratios with lower volcanic rates. A simple heat balance analysis suggests that the preponderance of volcanic systems must be open magmatic systems with respect to heat and matter transport in order to maintain eruptible magma at shallow depth throughout the observed lifetime of the volcano. The empirical upper limit of Å`10-2 km3/yr for magma eruption rate in systems with relatively high intrusive:extrusive ratios may be a consequence of the fundamental parameters

  15. Derivation of intermediate to silicic magma from the basalt analyzed at the Vega 2 landing site, Venus.

    Science.gov (United States)

    Shellnutt, J Gregory

    2018-01-01

    Geochemical modeling using the basalt composition analyzed at the Vega 2 landing site indicates that intermediate to silicic liquids can be generated by fractional crystallization and equilibrium partial melting. Fractional crystallization modeling using variable pressures (0.01 GPa to 0.5 G